Python: Add self-validating CFG tests

These tests consist of various Python constructions (hopefully a
somewhat comprehensive set) with specific timestamp annotations
scattered throughout. When the tests are run using the Python 3
interpreter, these annotations are checked and compared to the "current
timestamp" to see that they are in agreement. This is what makes the
tests "self-validating".

There are a few different kinds of annotations: the basic `t[4]` style
(meaning this is executed at timestamp 4), the `t[dead(4)]` variant
(meaning this _would_ happen at timestamp 4, but it is in a dead
branch), and `t[never]` (meaning this is never executed at all).

In addition to this, there is a query, MissingAnnotations, which checks
whether we have applied these annotations maximally. Many expression
nodes are not actually annotatable, so there is a sizeable list of
excluded nodes for that query.
This commit is contained in:
Taus
2026-04-28 15:06:30 +00:00
parent 1ba9601257
commit 795b138584
23 changed files with 2500 additions and 0 deletions

View File

@@ -0,0 +1,15 @@
/**
* Finds expressions in test functions that lack a timer annotation
* and are not part of the timer mechanism or otherwise excluded.
* An empty result means every annotatable expression is covered.
*/
import python
import TimerUtils
from TestFunction f, Expr e
where
e.getScope().getEnclosingScope*() = f and
not isTimerMechanism(e, f) and
not isUnannotatable(e)
select e, "Missing annotation in $@", f, f.getName()

View File

@@ -0,0 +1,16 @@
/**
* Implementation of the evaluation-order CFG signature using the existing
* Python control flow graph.
*/
private import python as Py
import TimerUtils
/** Existing Python CFG implementation of the evaluation-order signature. */
module OldCfg implements EvalOrderCfgSig {
class CfgNode = Py::ControlFlowNode;
class BasicBlock = Py::BasicBlock;
CfgNode scopeGetEntryNode(Py::Scope s) { result = s.getEntryNode() }
}

View File

@@ -0,0 +1,620 @@
/**
* Utility library for identifying timer annotations in evaluation-order tests.
*
* Identifies `expr @ t[n]` (matmul), `t(expr, n)` (call), and
* `expr @ t.dead[n]` (dead-code) patterns, extracts timestamp values,
* and provides predicates for traversing consecutive annotated CFG nodes.
*/
private import python
/**
* A function decorated with `@test` from the timer module.
* The first parameter is the timer object.
*/
class TestFunction extends Function {
TestFunction() {
this.getADecorator().(Name).getId() = "test" and
this.getPositionalParameterCount() >= 1
}
/** Gets the name of the timer parameter (first parameter). */
string getTimerParamName() { result = this.getArgName(0) }
}
/** Gets an IntegerLiteral from a timestamp expression (single int or tuple of ints). */
private IntegerLiteral timestampLiteral(Expr timestamps) {
result = timestamps
or
result = timestamps.(Tuple).getAnElt()
}
/**
* Gets an element from a timestamp subscript index. Each element is either
* an `IntegerLiteral` (live), a `Call` to `dead` (dead), a `Name("never")`
* (never), or a tuple containing any mix of these.
*/
private Expr timestampElement(Expr timestamps) {
result = timestamps and not timestamps instanceof Tuple
or
result = timestamps.(Tuple).getAnElt()
}
/** Gets a live timestamp value from a subscript index expression. */
private IntegerLiteral liveTimestampLiteral(Expr timestamps) {
result = timestampElement(timestamps) and
not result = any(Call c).getAnArg()
}
/** Gets a dead timestamp value from a subscript index expression. */
private IntegerLiteral deadTimestampLiteral(Expr timestamps) {
exists(Call c |
c = timestampElement(timestamps) and
c.getFunc().(Name).getId() = "dead" and
result = c.getArg(0)
)
}
/** Holds if the subscript index contains `never`. */
private predicate hasNever(Expr timestamps) {
timestampElement(timestamps).(Name).getId() = "never"
}
/** A timer annotation in the AST. */
private newtype TTimerAnnotation =
/** `expr @ t[n]` or `expr @ t[n, m, ...]` or `expr @ t[dead(n), m, never]` */
TMatmulAnnotation(TestFunction func, Expr annotated, Expr timestamps) {
exists(BinaryExpr be |
be.getOp() instanceof MatMult and
be.getRight().(Subscript).getObject().(Name).getId() = func.getTimerParamName() and
be.getScope().getEnclosingScope*() = func and
annotated = be.getLeft() and
timestamps = be.getRight().(Subscript).getIndex()
)
} or
/** `t(expr, n)` */
TCallAnnotation(TestFunction func, Expr annotated, Expr timestamps) {
exists(Call call |
call.getFunc().(Name).getId() = func.getTimerParamName() and
call.getScope().getEnclosingScope*() = func and
annotated = call.getArg(0) and
timestamps = call.getArg(1)
)
}
/** A timer annotation (wrapping the newtype for a clean API). */
class TimerAnnotation extends TTimerAnnotation {
/** Gets a live timestamp value from this annotation. */
int getATimestamp() { exists(this.getTimestampExpr(result)) }
/** Gets the source expression for live timestamp value `ts`. */
IntegerLiteral getTimestampExpr(int ts) {
result = liveTimestampLiteral(this.getTimestampsExpr()) and
result.getValue() = ts
}
/** Gets a dead timestamp value from this annotation. */
int getADeadTimestamp() { exists(this.getDeadTimestampExpr(result)) }
/** Gets the source expression for dead timestamp value `ts`. */
IntegerLiteral getDeadTimestampExpr(int ts) {
result = deadTimestampLiteral(this.getTimestampsExpr()) and
result.getValue() = ts
}
/** Gets the raw timestamp expression (single element or tuple). */
abstract Expr getTimestampsExpr();
/** Gets the test function this annotation belongs to. */
abstract TestFunction getTestFunction();
/** Gets the annotated expression (the LHS of `@` or the first arg of `t(...)`). */
abstract Expr getAnnotatedExpr();
/** Gets the enclosing annotation expression (the `BinaryExpr` or `Call`). */
abstract Expr getTimerExpr();
/** Holds if timestamp `ts` is marked as dead in this annotation. */
predicate isDeadTimestamp(int ts) { ts = this.getADeadTimestamp() }
/** Holds if all timestamps in this annotation are dead (no live timestamps). */
predicate isDead() {
not exists(this.getATimestamp()) and
not this.isNever() and
exists(this.getADeadTimestamp())
}
/** Holds if this is a never-evaluated annotation (contains `never`). */
predicate isNever() { hasNever(this.getTimestampsExpr()) }
string toString() { result = this.getAnnotatedExpr().toString() }
Location getLocation() { result = this.getAnnotatedExpr().getLocation() }
}
/** A matmul-based timer annotation: `expr @ t[...]`. */
class MatmulTimerAnnotation extends TMatmulAnnotation, TimerAnnotation {
TestFunction func;
Expr annotated;
Expr timestamps;
MatmulTimerAnnotation() { this = TMatmulAnnotation(func, annotated, timestamps) }
override Expr getTimestampsExpr() { result = timestamps }
override TestFunction getTestFunction() { result = func }
override Expr getAnnotatedExpr() { result = annotated }
override BinaryExpr getTimerExpr() { result.getLeft() = annotated }
}
/** A call-based timer annotation: `t(expr, n)`. */
class CallTimerAnnotation extends TCallAnnotation, TimerAnnotation {
TestFunction func;
Expr annotated;
Expr timestamps;
CallTimerAnnotation() { this = TCallAnnotation(func, annotated, timestamps) }
override Expr getTimestampsExpr() { result = timestamps }
override TestFunction getTestFunction() { result = func }
override Expr getAnnotatedExpr() { result = annotated }
override Call getTimerExpr() { result.getArg(0) = annotated }
}
/**
* Signature module defining the CFG interface needed by evaluation-order tests.
* This allows the test utilities to be instantiated with different CFG implementations.
*/
signature module EvalOrderCfgSig {
/** A control flow node. */
class CfgNode {
/** Gets a textual representation of this node. */
string toString();
/** Gets the location of this node. */
Location getLocation();
/** Gets the AST node corresponding to this CFG node, if any. */
AstNode getNode();
/** Gets a successor of this CFG node (including exceptional). */
CfgNode getASuccessor();
/** Gets a true-branch successor of this CFG node, if any. */
CfgNode getATrueSuccessor();
/** Gets a false-branch successor of this CFG node, if any. */
CfgNode getAFalseSuccessor();
/** Gets an exceptional successor of this CFG node. */
CfgNode getAnExceptionalSuccessor();
/** Gets the scope containing this CFG node. */
Scope getScope();
/** Gets the basic block containing this CFG node. */
BasicBlock getBasicBlock();
}
/** A basic block in the control flow graph. */
class BasicBlock {
/** Gets the CFG node at position `n` in this basic block. */
CfgNode getNode(int n);
/** Holds if this basic block reaches `bb` (reflexive). */
predicate reaches(BasicBlock bb);
/** Holds if this basic block strictly reaches `bb` (non-reflexive). */
predicate strictlyReaches(BasicBlock bb);
/** Holds if this basic block strictly dominates `bb`. */
predicate strictlyDominates(BasicBlock bb);
}
/** Gets the entry CFG node for scope `s`. */
CfgNode scopeGetEntryNode(Scope s);
}
/**
* Parameterised module providing CFG-dependent utilities for evaluation-order tests.
* Instantiate with a specific CFG implementation to get `TimerCfgNode` and related predicates.
*/
module EvalOrderCfgUtils<EvalOrderCfgSig Input> {
/** The CFG node type from the underlying implementation. */
final class CfgNode = Input::CfgNode;
/** The basic block type from the underlying implementation (named to avoid clash with `python::BasicBlock`). */
final class CfgBasicBlock = Input::BasicBlock;
/** Gets the entry CFG node for scope `s`. */
CfgNode scopeGetEntryNode(Scope s) { result = Input::scopeGetEntryNode(s) }
/**
* A CFG node corresponding to a timer annotation.
*/
class TimerCfgNode extends CfgNode {
private TimerAnnotation annot;
TimerCfgNode() { annot.getAnnotatedExpr() = this.getNode() }
/** Gets a timestamp value from this annotation. */
int getATimestamp() { result = annot.getATimestamp() }
/** Gets the source expression for timestamp value `ts`. */
IntegerLiteral getTimestampExpr(int ts) { result = annot.getTimestampExpr(ts) }
/** Gets the test function this annotation belongs to. */
TestFunction getTestFunction() { result = annot.getTestFunction() }
/** Holds if timestamp `ts` is marked as dead. */
predicate isDeadTimestamp(int ts) { annot.isDeadTimestamp(ts) }
/** Holds if all timestamps in this annotation are dead. */
predicate isDead() { annot.isDead() }
/** Holds if this is a never-evaluated annotation. */
predicate isNever() { annot.isNever() }
}
/**
* Holds if `next` is the next timer annotation reachable from `n` via
* CFG successors (both normal and exceptional), skipping non-annotated
* intermediaries within the same scope.
*/
predicate nextTimerAnnotation(CfgNode n, TimerCfgNode next) {
next = n.getASuccessor() and
next.getScope() = n.getScope()
or
exists(CfgNode mid |
mid = n.getASuccessor() and
not mid instanceof TimerCfgNode and
mid.getScope() = n.getScope() and
nextTimerAnnotation(mid, next)
)
}
/**
* Holds if `next` is the next timer annotation reachable from `n` via
* the true branch, skipping non-annotated intermediaries and after-value
* nodes for the same AST node.
*/
predicate nextTimerAnnotationFromTrue(CfgNode n, TimerCfgNode next) {
exists(CfgNode trueSucc |
trueSucc = n.getATrueSuccessor() and
trueSucc.getScope() = n.getScope()
|
// If the true successor is a different annotated node, use it
next = trueSucc and next.getNode() != n.getNode()
or
// Otherwise skip through it (it's an after-value node for the same expr)
nextTimerAnnotation(trueSucc, next)
)
}
/**
* Holds if `next` is the next timer annotation reachable from `n` via
* the false branch, skipping non-annotated intermediaries and after-value
* nodes for the same AST node.
*/
predicate nextTimerAnnotationFromFalse(CfgNode n, TimerCfgNode next) {
exists(CfgNode falseSucc |
falseSucc = n.getAFalseSuccessor() and
falseSucc.getScope() = n.getScope()
|
// If the false successor is a different annotated node, use it
next = falseSucc and next.getNode() != n.getNode()
or
// Otherwise skip through it (it's an after-value node for the same expr)
nextTimerAnnotation(falseSucc, next)
)
}
/** CFG-dependent test predicates, one per evaluation-order query. */
module CfgTests {
/**
* Holds if live annotation `a` in function `f` is unreachable from
* the function entry in the CFG.
*/
predicate allLiveReachable(TimerCfgNode a, TestFunction f) {
not a.isDead() and
f = a.getTestFunction() and
a.getScope() = f and
not scopeGetEntryNode(f).getBasicBlock().reaches(a.getBasicBlock())
}
/**
* Holds if annotated node `a` is followed by unannotated `succ` in the
* same basic block.
*/
predicate basicBlockAnnotationGap(TimerCfgNode a, CfgNode succ) {
exists(CfgBasicBlock bb, int i |
a = bb.getNode(i) and
succ = bb.getNode(i + 1)
) and
not succ instanceof TimerCfgNode and
not isUnannotatable(succ.getNode()) and
not isTimerMechanism(succ.getNode(), a.getTestFunction()) and
not exists(a.getAnExceptionalSuccessor()) and
succ.getNode() instanceof Expr
}
/**
* Holds if annotations `a` and `b` appear in the same basic block with
* `a` before `b`, but `a`'s minimum timestamp is not less than `b`'s.
*/
predicate basicBlockOrdering(TimerCfgNode a, TimerCfgNode b, int minA, int minB) {
exists(CfgBasicBlock bb, int i, int j | a = bb.getNode(i) and b = bb.getNode(j) and i < j) and
minA = min(a.getATimestamp()) and
minB = min(b.getATimestamp()) and
minA >= minB
}
/**
* Holds if function `f` has an annotation in a nested scope
* (generator, async function, comprehension, lambda).
*/
private predicate hasNestedScopeAnnotation(TestFunction f) {
exists(TimerAnnotation a |
a.getTestFunction() = f and
a.getAnnotatedExpr().getScope() != f
)
}
/**
* Holds if annotation `ann` with timestamp `a` has no consecutive
* successor (expected `a + 1`) in the CFG.
*/
predicate consecutiveTimestamps(TimerAnnotation ann, int a) {
not hasNestedScopeAnnotation(ann.getTestFunction()) and
not ann.isDead() and
a = ann.getATimestamp() and
not exists(TimerCfgNode x, TimerCfgNode y |
ann.getAnnotatedExpr() = x.getNode() and
nextTimerAnnotation(x, y) and
(a + 1) = y.getATimestamp()
) and
// Exclude the maximum timestamp in the function (it has no successor)
not a =
max(TimerAnnotation other |
other.getTestFunction() = ann.getTestFunction()
|
other.getATimestamp()
)
}
/**
* Holds if the expression annotated with `t.never` is reachable from
* its scope's entry.
*/
predicate neverReachable(TimerAnnotation ann) {
ann.isNever() and
exists(CfgNode n, Scope s |
n.getNode() = ann.getAnnotatedExpr() and
s = n.getScope() and
(
// Reachable via inter-block path (includes same block)
scopeGetEntryNode(s).getBasicBlock().reaches(n.getBasicBlock())
or
// In same block as entry but at a later index
exists(CfgBasicBlock bb, int i, int j |
bb.getNode(i) = scopeGetEntryNode(s) and bb.getNode(j) = n and i < j
)
)
)
}
/**
* Holds if consecutive annotated nodes `a` -> `b` have backward time
* flow (`minA >= maxB`).
*/
predicate noBackwardFlow(TimerCfgNode a, TimerCfgNode b, int minA, int maxB) {
nextTimerAnnotation(a, b) and
not a.isDead() and
not b.isDead() and
minA = min(a.getATimestamp()) and
maxB = max(b.getATimestamp()) and
minA >= maxB
}
/**
* Holds if annotations `a` and `b` share timestamp `ts` but `a`
* can reach `b` in the CFG.
*/
predicate noSharedReachable(TimerCfgNode a, TimerCfgNode b, int ts) {
a != b and
not a.isDead() and
not b.isDead() and
a.getTestFunction() = b.getTestFunction() and
ts = a.getATimestamp() and
ts = b.getATimestamp() and
(
a.getBasicBlock().strictlyReaches(b.getBasicBlock())
or
exists(CfgBasicBlock bb, int i, int j | a = bb.getNode(i) and b = bb.getNode(j) and i < j)
)
}
/**
* Holds if consecutive single-timestamp annotations `a` -> `b` on a
* forward edge have `maxA >= minB`.
*/
predicate strictForward(TimerCfgNode a, TimerCfgNode b, int maxA, int minB) {
nextTimerAnnotation(a, b) and
not a.isDead() and
not b.isDead() and
// Only apply to non-loop code (single timestamps on both sides)
strictcount(a.getATimestamp()) = 1 and
strictcount(b.getATimestamp()) = 1 and
// Forward edge: B does not strictly dominate A (excludes loop back-edges
// but still checks same-basic-block pairs)
not b.getBasicBlock().strictlyDominates(a.getBasicBlock()) and
maxA = max(a.getATimestamp()) and
minB = min(b.getATimestamp()) and
maxA >= minB
}
/**
* Holds if CFG node `n` in test function `f` does not belong to any basic block.
*/
predicate noBasicBlock(CfgNode n, TestFunction f) {
n.getScope() = f and
not exists(n.getBasicBlock())
}
/**
* Holds if non-dead annotation `ann` has no corresponding CFG node.
*/
predicate annotationWithoutCfgNode(TimerAnnotation ann) {
not ann.isDead() and
not ann.isNever() and
not exists(CfgNode n | n.getNode() = ann.getAnnotatedExpr())
}
predicate annotationWithCfgNode(TimerAnnotation ann) {
exists(CfgNode n | n.getNode() = ann.getAnnotatedExpr())
}
/**
* Holds if annotation `ann` with timestamp `a` has no consecutive
* predecessor (expected `a - 1`) in the CFG.
*/
predicate consecutivePredecessorTimestamps(TimerAnnotation ann, int a) {
not hasNestedScopeAnnotation(ann.getTestFunction()) and
not ann.isDead() and
a = ann.getATimestamp() and
not exists(TimerCfgNode x, TimerCfgNode y |
ann.getAnnotatedExpr() = y.getNode() and
nextTimerAnnotation(x, y) and
(a - 1) = x.getATimestamp()
) and
// Exclude the minimum timestamp in the function (it has no predecessor)
not a =
min(TimerAnnotation other |
other.getTestFunction() = ann.getTestFunction() and
not other.isDead()
|
other.getATimestamp()
)
}
/**
* Holds if `node` has both a true and false successor, but the true
* successor's timestamp `ts` is not marked as dead on the false
* successor (or vice versa).
*
* This checks that boolean branches are properly annotated: when a
* condition splits into true/false paths, the next annotated node
* on each side should account for the other side's timestamps as dead.
*/
predicate missingBranchTimestamp(TimerCfgNode node, int ts, string branch) {
not hasNestedScopeAnnotation(node.getTestFunction()) and
exists(TimerCfgNode trueNext, TimerCfgNode falseNext |
nextTimerAnnotationFromTrue(node, trueNext) and
nextTimerAnnotationFromFalse(node, falseNext) and
trueNext != falseNext
|
// True successor has live timestamp ts, but false successor
// doesn't have it as dead
ts = trueNext.getATimestamp() and
not falseNext.isDeadTimestamp(ts) and
not ts = falseNext.getATimestamp() and
branch = "false"
or
// False successor has live timestamp ts, but true successor
// doesn't have it as dead
ts = falseNext.getATimestamp() and
not trueNext.isDeadTimestamp(ts) and
not ts = trueNext.getATimestamp() and
branch = "true"
)
}
}
}
/**
* Holds if `e` is part of the timer mechanism: a top-level timer
* expression or a (transitive) sub-expression of one.
*/
predicate isTimerMechanism(Expr e, TestFunction f) {
exists(TimerAnnotation a |
a.getTestFunction() = f and
e = a.getTimerExpr().getASubExpression*()
)
}
/**
* Holds if expression `e` cannot be annotated due to Python syntax
* limitations (e.g., it is a definition target, a pattern, or part
* of a decorator application).
*/
predicate isUnannotatable(Expr e) {
// Function/class definitions
e instanceof FunctionExpr
or
e instanceof ClassExpr
or
// Docstrings are string literals used as expression statements
e instanceof StringLiteral and e.getParent() instanceof ExprStmt
or
// Function parameters are bound by the call, not evaluated in the body
e instanceof Parameter
or
// Name nodes that are definitions or deletions (assignment targets, def/class
// name bindings, augmented assignment targets, for-loop targets, del targets)
e.(Name).isDefinition()
or
e.(Name).isDeletion()
or
// Tuple/List/Starred nodes in assignment or for-loop targets are
// structural unpack patterns, not evaluations
(e instanceof Tuple or e instanceof List or e instanceof Starred) and
e = any(AssignStmt a).getATarget().getASubExpression*()
or
(e instanceof Tuple or e instanceof List or e instanceof Starred) and
e = any(For f).getTarget().getASubExpression*()
or
// The decorator call node wrapping a function/class definition,
// and its sub-expressions (the decorator name itself)
e = any(FunctionExpr func).getADecoratorCall().getASubExpression*()
or
e = any(ClassExpr cls).getADecoratorCall().getASubExpression*()
or
// Augmented assignment (x += e): the implicit BinaryExpr for the operation
e = any(AugAssign aug).getOperation()
or
// with-statement `as` variables are bindings
(e instanceof Name or e instanceof Tuple or e instanceof List) and
e = any(With w).getOptionalVars().getASubExpression*()
or
// except-clause exception type and `as` variable are part of except syntax
exists(ExceptStmt ex | e = ex.getType() or e = ex.getName())
or
// match/case pattern expressions are part of pattern syntax
e.getParent+() instanceof Pattern
or
// Subscript/Attribute nodes on the LHS of an assignment are store
// operations, not value expressions (including nested ones like d["a"][1])
(e instanceof Subscript or e instanceof Attribute) and
e = any(AssignStmt a).getATarget().getASubExpression*()
or
// Match/case guard nodes are part of case syntax
e instanceof Guard
or
// Yield/YieldFrom in statement position — the return value is
// discarded and cannot be meaningfully annotated
(e instanceof Yield or e instanceof YieldFrom) and
e.getParent() instanceof ExprStmt
or
// Synthetic nodes inside desugared comprehensions
e.getScope() = any(Comp c).getFunction() and
(
e.(Name).getId() = ".0"
or
e instanceof Tuple and e.getParent() instanceof Yield
)
}

View File

@@ -0,0 +1,56 @@
"""Assert and raise statement evaluation order."""
from timer import test, dead
@test
def test_assert_true(t):
x = True @ t[0]
assert x @ t[1]
y = 1 @ t[2]
@test
def test_assert_true_with_message(t):
x = True @ t[0]
assert x @ t[1], "msg" @ t[dead(2)]
y = 1 @ t[2]
@test
def test_assert_false_caught(t):
try:
x = False @ t[0]
assert x @ t[1], "fail" @ t[2]
except AssertionError:
y = 1 @ t[3]
@test
def test_raise_caught(t):
try:
x = 1 @ t[0]
raise ((ValueError @ t[1])("test" @ t[2]) @ t[3])
except ValueError:
y = 2 @ t[4]
@test
def test_raise_from_caught(t):
try:
x = 1 @ t[0]
raise ((ValueError @ t[1])("test" @ t[2]) @ t[3]) from ((RuntimeError @ t[4])("cause" @ t[5]) @ t[6])
except ValueError:
y = 2 @ t[7]
@test
def test_bare_reraise(t):
try:
try:
raise ((ValueError @ t[0])("test" @ t[1]) @ t[2])
except ValueError:
x = 1 @ t[3]
raise
except ValueError:
y = 2 @ t[4]

View File

@@ -0,0 +1,97 @@
"""Async/await evaluation order tests.
Coroutine bodies are lazy — like generators, the body runs only when
awaited (or driven by the event loop). asyncio.run() drives the
coroutine to completion synchronously from the caller's perspective.
"""
import asyncio
from contextlib import asynccontextmanager
from timer import test
@test
def test_simple_async(t):
"""Simple async function: body runs inside asyncio.run()."""
async def coro():
x = 1 @ t[4]
return x @ t[5]
result = ((asyncio @ t[0]).run @ t[1])((coro @ t[2])() @ t[3]) @ t[6]
@test
def test_await_expression(t):
"""await suspends the caller until the inner coroutine completes."""
async def helper():
return 1 @ t[4]
async def main():
x = await helper() @ t[5]
return x @ t[6]
result = ((asyncio @ t[0]).run @ t[1])((main @ t[2])() @ t[3]) @ t[7]
@test
def test_async_for(t):
"""async for iterates an async generator."""
async def agen():
yield 1 @ t[5]
yield 2 @ t[7]
async def main():
async for val in agen() @ t[4]:
val @ t[6, 8]
((asyncio @ t[0]).run @ t[1])((main @ t[2])() @ t[3]) @ t[9]
@test
def test_async_with(t):
"""async with enters/exits an async context manager."""
@asynccontextmanager
async def ctx():
yield 1 @ t[5]
async def main():
async with ctx() @ t[4] as val:
val @ t[6]
((asyncio @ t[0]).run @ t[1])((main @ t[2])() @ t[3]) @ t[7]
@test
def test_multiple_awaits(t):
"""Sequential awaits in one coroutine."""
async def task_a():
return 10 @ t[4]
async def task_b():
return 20 @ t[6]
async def main():
a = await task_a() @ t[5]
b = await task_b() @ t[7]
return (a @ t[8] + b @ t[9]) @ t[10]
result = ((asyncio @ t[0]).run @ t[1])((main @ t[2])() @ t[3]) @ t[11]
@test
def test_gather(t):
"""asyncio.gather schedules coroutines as concurrent tasks."""
async def task_a():
return 1 @ t[6]
async def task_b():
return 2 @ t[7]
async def main():
results = await asyncio.gather(
task_a() @ t[4],
task_b() @ t[5],
) @ t[8]
return results @ t[9]
result = ((asyncio @ t[0]).run @ t[1])((main @ t[2])() @ t[3]) @ t[10]

View File

@@ -0,0 +1,53 @@
"""Augmented assignment evaluation order."""
from timer import test
@test
def test_plus_equals(t):
x = 1 @ t[0]
x += 2 @ t[1]
y = x @ t[2]
@test
def test_sub_mul_div(t):
x = 20 @ t[0]
x -= 5 @ t[1]
x *= 2 @ t[2]
x /= 6 @ t[3]
x = 17 @ t[4]
x //= 3 @ t[5]
x %= 3 @ t[6]
y = x @ t[7]
@test
def test_power_equals(t):
x = 2 @ t[0]
x **= 3 @ t[1]
y = x @ t[2]
@test
def test_bitwise_equals(t):
x = 0b1111 @ t[0]
x &= 0b1010 @ t[1]
x |= 0b0101 @ t[2]
x ^= 0b0011 @ t[3]
y = x @ t[4]
@test
def test_shift_equals(t):
x = 1 @ t[0]
x <<= 4 @ t[1]
x >>= 2 @ t[2]
y = x @ t[3]
@test
def test_list_extend(t):
x = [1 @ t[0], 2 @ t[1]] @ t[2]
x += [3 @ t[3], 4 @ t[4]] @ t[5]
y = x @ t[6]

View File

@@ -0,0 +1,223 @@
"""Basic expression evaluation order.
These tests verify that sub-expressions within a single expression
are evaluated in the expected order (typically left to right for
operands of binary operators, elements of collection literals, etc.)
Every evaluated expression has a timestamp annotation, except the
timer mechanism itself (t[n], t.dead[n]).
"""
from timer import test, never
@test
def test_sequential_statements(t):
"""Statements execute top to bottom."""
x = 1 @ t[0]
y = 2 @ t[1]
z = 3 @ t[2]
@test
def test_binary_add(t):
"""In a + b, left operand evaluates before right."""
x = (1 @ t[0] + 2 @ t[1]) @ t[2]
@test
def test_binary_subtract(t):
"""In a - b, left operand evaluates before right."""
x = (10 @ t[0] - 3 @ t[1]) @ t[2]
@test
def test_binary_multiply(t):
"""In a * b, left operand evaluates before right."""
x = ((3 @ t[0]) * (4 @ t[1])) @ t[2]
@test
def test_nested_binary(t):
"""Sub-expressions evaluate before their containing expression."""
x = ((1 @ t[0] + 2 @ t[1]) @ t[2] + (3 @ t[3] + 4 @ t[4]) @ t[5]) @ t[6]
@test
def test_chained_add(t):
"""a + b + c is (a + b) + c: left to right."""
x = ((1 @ t[0] + 2 @ t[1]) @ t[2] + 3 @ t[3]) @ t[4]
@test
def test_mixed_precedence(t):
"""In a + b * c, all operands still evaluate left to right."""
x = (1 @ t[0] + ((2 @ t[1]) * (3 @ t[2])) @ t[3]) @ t[4]
@test
def test_string_concat(t):
"""String concatenation operands: left to right."""
x = (("hello" @ t[0] + " " @ t[1]) @ t[2] + "world" @ t[3]) @ t[4]
@test
def test_comparison(t):
"""In a < b, left operand evaluates before right."""
x = (1 @ t[0] < 2 @ t[1]) @ t[2]
@test
def test_chained_comparison(t):
"""Chained a < b < c: all evaluated left to right (b only once)."""
x = (1 @ t[0] < 2 @ t[1] < 3 @ t[2]) @ t[3]
@test
def test_list_elements(t):
"""List elements evaluate left to right."""
x = [1 @ t[0], 2 @ t[1], 3 @ t[2]] @ t[3]
@test
def test_dict_entries(t):
"""Dict: key before value, entries left to right."""
d = {1 @ t[0]: "a" @ t[1], 2 @ t[2]: "b" @ t[3]} @ t[4]
@test
def test_tuple_elements(t):
"""Tuple elements evaluate left to right."""
x = (1 @ t[0], 2 @ t[1], 3 @ t[2]) @ t[3]
@test
def test_set_elements(t):
"""Set elements evaluate left to right."""
x = {1 @ t[0], 2 @ t[1], 3 @ t[2]} @ t[3]
@test
def test_subscript(t):
"""In obj[idx], object evaluates before index."""
x = ([10 @ t[0], 20 @ t[1], 30 @ t[2]] @ t[3])[1 @ t[4]] @ t[5]
@test
def test_slice(t):
"""Slice parameters: object, then start, then stop."""
x = ([1 @ t[0], 2 @ t[1], 3 @ t[2], 4 @ t[3], 5 @ t[4]] @ t[5])[1 @ t[6]:3 @ t[7]] @ t[8]
@test
def test_method_call(t):
"""Object evaluated, then attribute lookup, then arguments left to right, then call."""
x = (("hello world" @ t[0]).replace @ t[1])("world" @ t[2], "there" @ t[3]) @ t[4]
@test
def test_method_chaining(t):
"""Chained method calls: left to right."""
x = ((((" hello " @ t[0]).strip @ t[1])() @ t[2]).upper @ t[3])() @ t[4]
@test
def test_unary_not(t):
"""Unary not: operand evaluated first."""
x = (not True @ t[0]) @ t[1]
@test
def test_unary_neg(t):
"""Unary negation: operand evaluated first."""
x = (-(3 @ t[0])) @ t[1]
@test
def test_multiple_assignment(t):
"""RHS evaluated once in x = y = expr."""
x = y = (1 @ t[0] + 2 @ t[1]) @ t[2]
@test
def test_callable_syntax(t):
"""t(value, n) is equivalent to value @ t[n]."""
x = (1 @ t[0] + 2 @ t[1]) @ t[2]
y = (x @ t[3] * 3 @ t[4]) @ t[5]
@test
def test_subscript_assign(t):
"""In obj[idx] = val, value is evaluated before target sub-expressions."""
lst = [0 @ t[0], 0 @ t[1], 0 @ t[2]] @ t[3]
(lst @ t[5])[1 @ t[6]] = 42 @ t[4]
x = lst @ t[7]
@test
def test_attribute_assign(t):
"""In obj.attr = val, value is evaluated before the object."""
class Obj:
pass
o = (Obj @ t[0])() @ t[1]
(o @ t[3]).x = 42 @ t[2]
y = (o @ t[4]).x @ t[5]
@test
def test_nested_subscript_assign(t):
"""Nested subscript assignment: val, then outer obj, then keys."""
d = {"a" @ t[0]: [0 @ t[1], 0 @ t[2]] @ t[3]} @ t[4]
(d @ t[6])["a" @ t[7]][1 @ t[8]] = 99 @ t[5]
x = d @ t[9]
@test
def test_unreachable_after_return(t):
"""Code after return has no CFG node."""
def f():
x = 1 @ t[1]
return x @ t[2]
y = 2 @ t[never]
result = (f @ t[0])() @ t[3]
@test
def test_none_literal(t):
"""None is a name constant."""
x = None @ t[0]
y = (x @ t[1] is None @ t[2]) @ t[3]
@test
def test_delete(t):
"""del statement removes a variable binding."""
x = 1 @ t[0]
del x
y = 2 @ t[1]
@test
def test_global(t):
"""global statement allows writing to module-level variable."""
global _test_global_var
_test_global_var = 1 @ t[0]
x = _test_global_var @ t[1]
@test
def test_nonlocal(t):
"""nonlocal statement allows inner function to rebind outer variable."""
x = 0 @ t[0]
def inner():
nonlocal x
x = 1 @ t[2]
(inner @ t[1])() @ t[3]
y = x @ t[4]
@test
def test_walrus(t):
"""Walrus operator := evaluates the RHS and binds it."""
if (y := 1 @ t[0]) @ t[1]:
z = y @ t[2]

View File

@@ -0,0 +1,76 @@
"""Short-circuit boolean operators and evaluation order."""
from timer import test, dead
@test
def test_and_both_sides(t):
# True and X — both operands evaluated, result is X
x = (True @ t[0] and 42 @ t[1, dead(2)]) @ t[dead(1), 2]
@test
def test_and_short_circuit(t):
# False and ... — right side never evaluated
x = (False @ t[0] and True @ t[dead(1)]) @ t[1, dead(2)]
@test
def test_or_short_circuit(t):
# True or ... — right side never evaluated
x = (True @ t[0] or False @ t[dead(1)]) @ t[1, dead(2)]
@test
def test_or_both_sides(t):
# False or X — both operands evaluated, result is X
x = (False @ t[0] or 42 @ t[1, dead(2)]) @ t[dead(1), 2]
@test
def test_not(t):
# not evaluates its operand, then negates
x = (not True @ t[0]) @ t[1]
y = (not False @ t[2]) @ t[3]
@test
def test_chained_and(t):
# 1 and 2 and 3 — all truthy, all evaluated left-to-right
x = (1 @ t[0] and 2 @ t[1, dead(3)] and 3 @ t[2, dead(3)]) @ t[dead(1), dead(2), 3]
@test
def test_chained_or(t):
# 0 or "" or 42 — first two falsy, all evaluated until truthy found
x = (0 @ t[0] or "" @ t[1, dead(3)] or 42 @ t[2, dead(3)]) @ t[dead(1), dead(2), 3]
@test
def test_mixed_and_or(t):
# True and False or 42 => (True and False) or 42 => False or 42 => 42
x = ((True @ t[0] and False @ t[1, dead(2)]) @ t[dead(1), 2, dead(4)] or 42 @ t[3, dead(4)]) @ t[dead(2), dead(3), 4]
@test
def test_and_side_effects(t):
# Both functions called when left side is truthy
def f():
return 10 @ t[1]
def g():
return 20 @ t[4]
x = ((f @ t[0])() @ t[2] and (g @ t[3])() @ t[5]) @ t[6]
@test
def test_or_side_effects(t):
# Both functions called when left side is falsy
def f():
return 0 @ t[1]
def g():
return 20 @ t[4]
x = ((f @ t[0])() @ t[2] or (g @ t[3])() @ t[5]) @ t[6]

View File

@@ -0,0 +1,74 @@
"""Class definitions — evaluation order."""
from timer import test
@test
def test_simple_class(t):
"""Simple class definition and instantiation."""
class Foo:
pass
obj = (Foo @ t[0])() @ t[1]
@test
def test_class_with_bases(t):
"""Base class expressions evaluated at class definition time."""
class Base:
pass
class Derived(Base @ t[0]):
pass
obj = (Derived @ t[1])() @ t[2]
@test
def test_class_with_methods(t):
"""Object evaluated before method is called."""
class Foo:
def greet(self, name):
return ("hello " @ t[5] + name @ t[6]) @ t[7]
obj = (Foo @ t[0])() @ t[1]
msg = ((obj @ t[2]).greet @ t[3])("world" @ t[4]) @ t[8]
@test
def test_class_instantiation(t):
"""Arguments to __init__ evaluate before instantiation completes."""
class Foo:
def __init__(self, x):
(self @ t[3]).x = x @ t[2]
obj = (Foo @ t[0])(42 @ t[1]) @ t[4]
val = (obj @ t[5]).x @ t[6]
@test
def test_method_call(t):
"""Method arguments evaluate left-to-right before the call."""
class Calculator:
def __init__(self, value):
(self @ t[3]).value = value @ t[2]
def add(self, x):
return ((self @ t[8]).value @ t[9] + x @ t[10]) @ t[11]
calc = (Calculator @ t[0])(10 @ t[1]) @ t[4]
result = ((calc @ t[5]).add @ t[6])(5 @ t[7]) @ t[12]
@test
def test_class_level_attribute(t):
"""Multiple attribute accesses in a single expression."""
class Config:
debug = True @ t[0]
version = 1 @ t[1]
x = ((Config @ t[2]).debug @ t[3], (Config @ t[4]).version @ t[5]) @ t[6]
@test
def test_class_decorator(t):
"""Decorator expression evaluated, class defined, then decorator called."""
def add_marker(cls):
(cls @ t[2]).marked = True @ t[1]
return cls @ t[3]
@(add_marker @ t[0])
class Foo:
pass
result = (Foo @ t[4]).marked @ t[5]

View File

@@ -0,0 +1,46 @@
"""Evaluation order tests for comprehensions and generator expressions."""
from timer import test
@test
def test_list_comprehension(t):
items = [1 @ t[0], 2 @ t[1], 3 @ t[2]] @ t[3]
result = [x @ t[5, 6, 7] for x in items @ t[4]] @ t[8]
@test
def test_filtered_comprehension(t):
items = [1 @ t[0], 2 @ t[1], 3 @ t[2], 4 @ t[3]] @ t[4]
result = [x @ t[14, 23] for x in items @ t[5] if (x @ t[6, 10, 15, 19] % 2 @ t[7, 11, 16, 20] == 0 @ t[8, 12, 17, 21]) @ t[9, 13, 18, 22]] @ t[24]
@test
def test_dict_comprehension(t):
items = [("a" @ t[0], 1 @ t[1]) @ t[2], ("b" @ t[3], 2 @ t[4]) @ t[5]] @ t[6]
result = {k @ t[8, 10]: v @ t[9, 11] for k, v in items @ t[7]} @ t[12]
@test
def test_set_comprehension(t):
items = [1 @ t[0], 2 @ t[1], 3 @ t[2]] @ t[3]
result = {x @ t[5, 6, 7] for x in items @ t[4]} @ t[8]
@test
def test_generator_expression(t):
items = [1 @ t[0], 2 @ t[1], 3 @ t[2]] @ t[3]
gen = (x @ t[8, 9, 10] for x in items @ t[4]) @ t[5]
result = (list @ t[6])(gen @ t[7]) @ t[11]
@test
def test_nested_comprehension(t):
matrix = [[1 @ t[0], 2 @ t[1]] @ t[2], [3 @ t[3], 4 @ t[4]] @ t[5]] @ t[6]
result = [x @ t[9, 10, 12, 13] for row in matrix @ t[7] for x in row @ t[8, 11]] @ t[14]
@test
def test_comprehension_with_call(t):
items = [1 @ t[0], 2 @ t[1], 3 @ t[2]] @ t[3]
result = [(str @ t[5, 8, 11])(x @ t[6, 9, 12]) @ t[7, 10, 13] for x in items @ t[4]] @ t[14]

View File

@@ -0,0 +1,44 @@
"""Ternary conditional expressions and evaluation order."""
from timer import test, dead
@test
def test_ternary_true(t):
# Condition is True — consequent evaluated, alternative skipped
x = (1 @ t[1] if True @ t[0] else 2 @ t[dead(1)]) @ t[2]
@test
def test_ternary_false(t):
# Condition is False — alternative evaluated, consequent skipped
x = (1 @ t[dead(1)] if False @ t[0] else 2 @ t[1]) @ t[2]
@test
def test_ternary_nested(t):
# Nested: outer condition True, inner condition True
# ((10 if C1 else 20) if C2 else 30) — C2 first, then C1, then 10
x = ((10 @ t[2] if True @ t[1] else 20 @ t[dead(2)]) @ t[3] if True @ t[0] else 30 @ t[dead(1)]) @ t[4]
@test
def test_ternary_assignment(t):
# Ternary result assigned, then used in later expression
value = (100 @ t[1] if True @ t[0] else 200 @ t[dead(1)]) @ t[2]
result = (value @ t[3] + 1 @ t[4]) @ t[5]
@test
def test_ternary_complex_expressions(t):
# Complex sub-expressions in condition and consequent
x = ((1 @ t[3] + 2 @ t[4]) @ t[5] if (3 @ t[0] > 2 @ t[1]) @ t[2] else (4 @ t[dead(3)] + 5 @ t[dead(4)]) @ t[dead(5)]) @ t[6]
@test
def test_ternary_as_argument(t):
# Ternary used as a function argument
def f(a):
return a @ t[4]
result = (f @ t[0])((1 @ t[2] if True @ t[1] else 2 @ t[dead(2)]) @ t[3]) @ t[5]

View File

@@ -0,0 +1,34 @@
"""F-string evaluation order."""
from timer import test
@test
def test_simple_fstring(t):
name = "world" @ t[0]
s = f"hello {name @ t[1]}" @ t[2]
@test
def test_multi_expr_fstring(t):
a = "hello" @ t[0]
b = "world" @ t[1]
s = f"{a @ t[2]} {b @ t[3]}" @ t[4]
@test
def test_nested_fstring(t):
inner = "world" @ t[0]
s = f"hello {f'dear {inner @ t[1]}' @ t[2]}" @ t[3]
@test
def test_format_spec(t):
x = 3.14159 @ t[0]
s = f"{x @ t[1]:.2f}" @ t[2]
@test
def test_method_in_fstring(t):
name = "world" @ t[0]
s = f"hello {((name @ t[1]).upper @ t[2])() @ t[3]}" @ t[4]

View File

@@ -0,0 +1,85 @@
"""Function calls and definitions — evaluation order."""
from timer import test
@test
def test_argument_order(t):
"""Arguments evaluate left-to-right before the call."""
def add(a, b):
return (a @ t[3] + b @ t[4]) @ t[5]
result = (add @ t[0])(1 @ t[1], 2 @ t[2]) @ t[6]
@test
def test_multiple_arguments(t):
"""All arguments left-to-right, then the call."""
def f(a, b, c):
return ((a @ t[4] + b @ t[5]) @ t[6] + c @ t[7]) @ t[8]
result = (f @ t[0])(1 @ t[1], 2 @ t[2], 3 @ t[3]) @ t[9]
@test
def test_default_arguments(t):
"""Default expressions are evaluated at definition time."""
val = 5 @ t[0]
def f(a, b=val @ t[1]):
return (a @ t[4] + b @ t[5]) @ t[6]
result = (f @ t[2])(10 @ t[3]) @ t[7]
@test
def test_args_kwargs(t):
"""*args and **kwargs — expressions evaluated before the call."""
def f(*args, **kwargs):
return ((sum @ t[9])(args @ t[10]) @ t[11] + (sum @ t[12])(((kwargs @ t[13]).values @ t[14])() @ t[15]) @ t[16]) @ t[17]
args = [1 @ t[0], 2 @ t[1]] @ t[2]
kwargs = {"c" @ t[3]: 3 @ t[4]} @ t[5]
result = (f @ t[6])(*args @ t[7], **kwargs @ t[8]) @ t[18]
@test
def test_nested_calls(t):
"""Inner call completes before becoming an argument to outer call."""
def f(x):
return (x @ t[7] + 1 @ t[8]) @ t[9]
def g(x):
return (x @ t[3] * 2 @ t[4]) @ t[5]
result = (f @ t[0])((g @ t[1])(1 @ t[2]) @ t[6]) @ t[10]
@test
def test_function_as_argument(t):
"""Function object is just another argument, evaluated left-to-right."""
def apply(fn, x):
return (fn @ t[3])(x @ t[4]) @ t[8]
def double(x):
return (x @ t[5] * 2 @ t[6]) @ t[7]
result = (apply @ t[0])(double @ t[1], 5 @ t[2]) @ t[9]
@test
def test_decorator(t):
"""Decorator: expression evaluated, function defined, decorator called."""
def my_decorator(fn):
return fn @ t[1]
@(my_decorator @ t[0])
def f():
return 42 @ t[3]
result = (f @ t[2])() @ t[4]
@test
def test_keyword_arguments(t):
"""Keyword argument values evaluate left-to-right."""
def f(a, b):
return (a @ t[3] + b @ t[4]) @ t[5]
result = (f @ t[0])(a=1 @ t[1], b=2 @ t[2]) @ t[6]
@test
def test_return_value(t):
"""The return value is just the result of the call expression."""
def f(x):
return (x @ t[2] * 2 @ t[3]) @ t[4]
result = (f @ t[0])(3 @ t[1]) @ t[5]

View File

@@ -0,0 +1,114 @@
"""If/elif/else control flow evaluation order."""
from timer import test, dead
@test
def test_if_true(t):
x = True @ t[0]
if x @ t[1]:
y = 1 @ t[2]
z = 0 @ t[3]
@test
def test_if_false(t):
x = False @ t[0]
if x @ t[1]:
y = 1 @ t[dead(2)]
z = 0 @ t[2]
@test
def test_if_else_true(t):
x = True @ t[0]
if x @ t[1]:
y = 1 @ t[2]
else:
y = 2 @ t[dead(2)]
z = 0 @ t[3]
@test
def test_if_else_false(t):
x = False @ t[0]
if x @ t[1]:
y = 1 @ t[dead(2)]
else:
y = 2 @ t[2]
z = 0 @ t[3]
@test
def test_if_elif_else_first(t):
x = 1 @ t[0]
if (x @ t[1] == 1 @ t[2]) @ t[3]:
y = "first" @ t[4]
elif (x @ t[dead(4)] == 2 @ t[dead(5)]) @ t[dead(6)]:
y = "second" @ t[dead(4)]
else:
y = "third" @ t[dead(4)]
z = 0 @ t[5]
@test
def test_if_elif_else_second(t):
x = 2 @ t[0]
if (x @ t[1] == 1 @ t[2]) @ t[3]:
y = "first" @ t[dead(7)]
elif (x @ t[4] == 2 @ t[5]) @ t[6]:
y = "second" @ t[7]
else:
y = "third" @ t[dead(7)]
z = 0 @ t[8]
@test
def test_if_elif_else_third(t):
x = 3 @ t[0]
if (x @ t[1] == 1 @ t[2]) @ t[3]:
y = "first" @ t[dead(7)]
elif (x @ t[4] == 2 @ t[5]) @ t[6]:
y = "second" @ t[dead(7)]
else:
y = "third" @ t[7]
z = 0 @ t[8]
@test
def test_nested_if_else(t):
x = True @ t[0]
y = True @ t[1]
if x @ t[2]:
if y @ t[3]:
z = 1 @ t[4]
else:
z = 2 @ t[dead(4)]
else:
z = 3 @ t[dead(4)]
w = 0 @ t[5]
@test
def test_if_compound_condition(t):
x = True @ t[0]
y = False @ t[1]
if (x @ t[2] and y @ t[3]) @ t[4]:
z = 1 @ t[dead(5)]
else:
z = 2 @ t[5]
w = 0 @ t[6]
@test
def test_if_pass(t):
x = True @ t[0]
if x @ t[1]:
pass
z = 0 @ t[2]
@test
@test

View File

@@ -0,0 +1,46 @@
"""Lambda expressions — evaluation order."""
from timer import test
@test
def test_simple_lambda(t):
"""Lambda creates a function object in one step."""
f = (lambda x: (x @ t[3] + 1 @ t[4]) @ t[5]) @ t[0]
result = (f @ t[1])(10 @ t[2]) @ t[6]
@test
def test_lambda_multiple_args(t):
"""Lambda call: arguments evaluate left to right."""
f = (lambda a, b, c: ((a @ t[5] + b @ t[6]) @ t[7] + c @ t[8]) @ t[9]) @ t[0]
result = (f @ t[1])(1 @ t[2], 2 @ t[3], 3 @ t[4]) @ t[10]
@test
def test_lambda_default(t):
"""Default argument evaluated at lambda creation time."""
val = 5 @ t[0]
f = (lambda x, y=val @ t[1]: (x @ t[5] + y @ t[6]) @ t[7]) @ t[2]
result = (f @ t[3])(10 @ t[4]) @ t[8]
@test
def test_lambda_map(t):
"""Lambda body runs once per element when consumed by list(map(...))."""
f = (lambda x: (x @ t[9, 12, 15] * 2 @ t[10, 13, 16]) @ t[11, 14, 17]) @ t[0]
result = (list @ t[1])((map @ t[2])(f @ t[3], [1 @ t[4], 2 @ t[5], 3 @ t[6]] @ t[7]) @ t[8]) @ t[18]
@test
def test_immediately_invoked(t):
"""Arguments evaluated, then immediately-invoked lambda called."""
result = ((lambda x: (x @ t[2] + 1 @ t[3]) @ t[4]) @ t[0])(10 @ t[1]) @ t[5]
@test
def test_lambda_closure(t):
"""Lambda captures enclosing scope; body runs at call time."""
x = 10 @ t[0]
f = (lambda: x @ t[3]) @ t[1]
result = (f @ t[2])() @ t[4]

View File

@@ -0,0 +1,146 @@
"""Loop control flow evaluation order tests."""
from timer import test, dead
# 1. Simple while loop (fixed iterations)
@test
def test_while_loop(t):
i = 0 @ t[0]
while (i @ t[1, 7, 13, 19] < 3 @ t[2, 8, 14, 20]) @ t[3, 9, 15, 21]: # 4 checks: 3 true + 1 false
i = (i @ t[4, 10, 16] + 1 @ t[5, 11, 17]) @ t[6, 12, 18]
done = True @ t[22]
# 2. While loop with break
@test
def test_while_break(t):
i = 0 @ t[0]
while (i @ t[1, 10, 19] < 5 @ t[2, 11, 20]) @ t[3, 12, 21]:
if (i @ t[4, 13, 22] == 2 @ t[5, 14, 23]) @ t[6, 15, 24]:
break
i = (i @ t[7, 16] + 1 @ t[8, 17]) @ t[9, 18]
done = True @ t[25]
# 3. While loop with continue
@test
def test_while_continue(t):
i = 0 @ t[0]
total = 0 @ t[1]
while (i @ t[2, 14, 23, 35] < 3 @ t[3, 15, 24, 36]) @ t[4, 16, 25, 37]:
i = (i @ t[5, 17, 26] + 1 @ t[6, 18, 27]) @ t[7, 19, 28]
if (i @ t[8, 20, 29] == 2 @ t[9, 21, 30]) @ t[10, 22, 31]:
continue
total = (total @ t[11, 32] + i @ t[12, 33]) @ t[13, 34]
done = True @ t[38]
# 4. While/else (no break — else executes)
@test
def test_while_else(t):
i = 0 @ t[0]
while (i @ t[1, 7, 13] < 2 @ t[2, 8, 14]) @ t[3, 9, 15]:
i = (i @ t[4, 10] + 1 @ t[5, 11]) @ t[6, 12]
else:
done = True @ t[16]
# 5. While/else (with break — else skipped)
@test
def test_while_else_break(t):
i = 0 @ t[0]
while (i @ t[1, 10] < 5 @ t[2, 11]) @ t[3, 12]:
if (i @ t[4, 13] == 1 @ t[5, 14]) @ t[6, 15]:
break
i = (i @ t[7] + 1 @ t[8]) @ t[9]
else:
never = True @ t[dead(16)]
after = True @ t[16]
# 6. Simple for loop over a list
@test
def test_for_list(t):
for x in [1 @ t[0], 2 @ t[1], 3 @ t[2]] @ t[3]:
x @ t[4, 5, 6]
done = True @ t[7]
# 7. For loop with range
@test
def test_for_range(t):
for i in (range @ t[0])(3 @ t[1]) @ t[2]:
i @ t[3, 4, 5]
done = True @ t[6]
# 8. For loop with break
@test
def test_for_break(t):
for x in [1 @ t[0], 2 @ t[1], 3 @ t[2], 4 @ t[3]] @ t[4]:
if (x @ t[5, 9, 13] == 3 @ t[6, 10, 14]) @ t[7, 11, 15]:
break
x @ t[8, 12]
done = True @ t[16]
# 9. For loop with continue
@test
def test_for_continue(t):
total = 0 @ t[0]
for x in [1 @ t[1], 2 @ t[2], 3 @ t[3]] @ t[4]:
if (x @ t[5, 11, 14] == 2 @ t[6, 12, 15]) @ t[7, 13, 16]:
continue
total = (total @ t[8, 17] + x @ t[9, 18]) @ t[10, 19]
done = True @ t[20]
# 10. For/else (no break — else executes)
@test
def test_for_else(t):
for x in [1 @ t[0], 2 @ t[1]] @ t[2]:
x @ t[3, 4]
else:
done = True @ t[5]
# 11. For/else (with break — else skipped)
@test
def test_for_else_break(t):
for x in [1 @ t[0], 2 @ t[1], 3 @ t[2]] @ t[3]:
if (x @ t[4, 8] == 2 @ t[5, 9]) @ t[6, 10]:
break
x @ t[7]
else:
never = True @ t[dead(11)]
after = True @ t[11]
# 12. Nested loops
@test
def test_nested_loops(t):
for i in [1 @ t[0], 2 @ t[1]] @ t[2]:
for j in [10 @ t[3, 12], 20 @ t[4, 13]] @ t[5, 14]:
(i @ t[6, 9, 15, 18, dead(21)] + j @ t[7, 10, 16, 19]) @ t[8, 11, 17, 20]
done = True @ t[dead(3), dead(6), dead(9), dead(12), dead(15), dead(18), 21]
# 13. While True with conditional break
@test
def test_while_true_break(t):
i = 0 @ t[0]
while True @ t[1, 8, 15]:
i = (i @ t[2, 9, 16] + 1 @ t[3, 10, 17]) @ t[4, 11, 18]
if (i @ t[5, 12, 19] == 3 @ t[6, 13, 20]) @ t[7, 14, 21]:
break
done = True @ t[22]
# 14. For with enumerate
@test
def test_for_enumerate(t):
for idx, val in (enumerate @ t[0])(["a" @ t[1], "b" @ t[2], "c" @ t[3]] @ t[4]) @ t[5]:
idx @ t[6, 8, 10]
val @ t[7, 9, 11]
done = True @ t[12]

View File

@@ -0,0 +1,173 @@
"""Evaluation order for match/case (structural pattern matching, Python 3.10+)."""
import sys
if sys.version_info < (3, 10):
print("Skipping match/case tests (requires Python 3.10+)")
print("---")
print("0/0 tests passed")
sys.exit(0)
from timer import test, dead, never
@test
def test_match_literal(t):
x = 1 @ t[0]
match x @ t[1]:
case 1:
y = "one" @ t[2]
case 2:
y = "two" @ t[dead(2)]
z = y @ t[3]
@test
def test_match_literal_fallthrough(t):
x = 3 @ t[0]
match x @ t[1]:
case 1:
y = "one" @ t[dead(2)]
case 2:
y = "two" @ t[dead(2)]
case 3:
y = "three" @ t[2]
z = y @ t[3]
@test
def test_match_wildcard(t):
x = 42 @ t[0]
match x @ t[1]:
case 1:
y = "one" @ t[dead(2)]
case _:
y = "other" @ t[2]
z = y @ t[3]
@test
def test_match_capture(t):
x = 42 @ t[0]
match x @ t[1]:
case n:
y = n @ t[2]
z = y @ t[3]
@test
def test_match_or_pattern(t):
x = 2 @ t[0]
match x @ t[1]:
case 1 | 2:
y = "low" @ t[2]
case _:
y = "other" @ t[dead(2)]
z = y @ t[3]
@test
def test_match_guard(t):
x = 5 @ t[0]
match x @ t[1]:
case n if (n @ t[2] > 3 @ t[3]) @ t[4]:
y = n @ t[5]
case _:
y = 0 @ t[dead(5)]
z = y @ t[6]
@test
def test_match_class_pattern(t):
x = 42 @ t[0]
match x @ t[1]:
case int():
y = "integer" @ t[2]
case str():
y = "string" @ t[dead(2)]
z = y @ t[3]
@test
def test_match_sequence(t):
x = [1 @ t[0], 2 @ t[1]] @ t[2]
match x @ t[3]:
case [a, b]:
y = (a @ t[4] + b @ t[5]) @ t[6]
case _:
y = 0 @ t[dead(6)]
z = y @ t[7]
@test
def test_match_mapping(t):
x = {"key" @ t[0]: 42 @ t[1]} @ t[2]
match x @ t[3]:
case {"key": value}:
y = value @ t[4]
case _:
y = 0 @ t[dead(4)]
z = y @ t[5]
@test
def test_match_nested(t):
x = {"users" @ t[0]: [{"name" @ t[1]: "Alice" @ t[2]} @ t[3]] @ t[4]} @ t[5]
match x @ t[6]:
case {"users": [{"name": name}]}:
y = name @ t[7]
case _:
y = "unknown" @ t[dead(7)]
z = y @ t[8]
@test
def test_match_or_pattern_with_as(t):
"""OR pattern with `as` binding and method call on the result."""
clause = "foo@bar" @ t[0]
match clause @ t[1]:
case (str() as uses) | {"uses": uses}:
result = ((uses @ t[2]).partition @ t[3])("@" @ t[4]) @ t[5]
x = (result @ t[6])[0 @ t[7]] @ t[8]
case _:
raise ((ValueError @ t[dead(2)])(clause @ t[dead(3)]) @ t[dead(4)])
y = x @ t[9]
@test
def test_match_wildcard_raise(t):
"""Wildcard case that raises, with OR pattern on the other branch."""
clause = 42 @ t[0]
try:
match clause @ t[1]:
case (str() as uses) | {"uses": uses}:
result = uses @ t[dead(2)]
case _:
raise ((ValueError @ t[2])(f"Invalid: {clause @ t[3]}" @ t[4]) @ t[5])
except ValueError:
y = 0 @ t[6]
@test
def test_match_exhaustive_return_first(t):
"""Every case returns; code after match is unreachable (first case taken)."""
def f(x):
match x @ t[2]:
case 1:
return "one" @ t[3]
case _:
return "other" @ t[dead(3)]
y = 0 @ t[never]
result = (f @ t[0])(1 @ t[1]) @ t[4]
@test
def test_match_exhaustive_return_wildcard(t):
"""Every case returns; code after match is unreachable (wildcard taken)."""
def f(x):
match x @ t[2]:
case 1:
return "one" @ t[dead(3)]
case _:
return "other" @ t[3]
y = 0 @ t[never]
result = (f @ t[0])(99 @ t[1]) @ t[4]

View File

@@ -0,0 +1,182 @@
"""Exception handling control flow: try/except/else/finally evaluation order."""
from timer import test, dead, never
# 1. try/except — no exception raised (except block skipped)
@test
def test_try_no_exception(t):
try:
x = 1 @ t[0]
y = 2 @ t[1]
except ValueError:
z = 3 @ t[dead(2)]
after = 0 @ t[2]
# 2. try/except — exception raised and caught
@test
def test_try_with_exception(t):
try:
x = 1 @ t[0]
raise ((ValueError @ t[1])() @ t[2])
y = 2 @ t[never]
except ValueError:
z = 3 @ t[3]
after = 0 @ t[4]
# 3. try/except/else — no exception (else runs)
@test
def test_try_except_else_no_exception(t):
try:
x = 1 @ t[0]
except ValueError:
y = 2 @ t[dead(1)]
else:
z = 3 @ t[1]
after = 0 @ t[2]
# 4. try/except/else — exception raised (else skipped)
@test
def test_try_except_else_with_exception(t):
try:
x = 1 @ t[0]
raise ((ValueError @ t[1])() @ t[2])
except ValueError:
y = 2 @ t[3]
else:
z = 3 @ t[dead(3)]
after = 0 @ t[4]
# 5. try/finally — no exception
@test
def test_try_finally_no_exception(t):
try:
x = 1 @ t[0]
y = 2 @ t[1]
finally:
z = 3 @ t[2]
after = 0 @ t[3]
# 6. try/finally — exception raised (finally runs, then exception propagates)
@test
def test_try_finally_exception(t):
try:
try:
x = 1 @ t[0]
raise ((ValueError @ t[1])() @ t[2])
finally:
y = 2 @ t[3]
except ValueError:
z = 3 @ t[4]
# 7. try/except/finally — no exception
@test
def test_try_except_finally_no_exception(t):
try:
x = 1 @ t[0]
except ValueError:
y = 2 @ t[dead(1)]
finally:
z = 3 @ t[1]
after = 0 @ t[2]
# 8. try/except/finally — exception caught
@test
def test_try_except_finally_exception(t):
try:
x = 1 @ t[0]
raise ((ValueError @ t[1])() @ t[2])
except ValueError:
y = 2 @ t[3]
finally:
z = 3 @ t[4]
after = 0 @ t[5]
# 9. Multiple except clauses — first matching
@test
def test_multiple_except_first(t):
try:
x = 1 @ t[0]
raise ((ValueError @ t[1])() @ t[2])
except ValueError:
y = 2 @ t[3]
except TypeError:
z = 3 @ t[dead(3)]
after = 0 @ t[4]
# 10. Multiple except clauses — second matching
@test
def test_multiple_except_second(t):
try:
x = 1 @ t[0]
raise ((TypeError @ t[1])() @ t[2])
except ValueError:
y = 2 @ t[dead(3)]
except TypeError:
z = 3 @ t[3]
after = 0 @ t[4]
# 11. except with `as` binding
@test
def test_except_as_binding(t):
try:
x = 1 @ t[0]
raise ((ValueError @ t[1])("msg" @ t[2]) @ t[3])
except ValueError as e:
y = (str @ t[4])(e @ t[5]) @ t[6]
after = 0 @ t[7]
# 12. Nested try/except
@test
def test_nested_try_except(t):
try:
x = 1 @ t[0]
try:
y = 2 @ t[1]
raise ((ValueError @ t[2])() @ t[3])
except ValueError:
z = 3 @ t[4]
w = 4 @ t[5]
except TypeError:
v = 5 @ t[dead(6)]
after = 0 @ t[6]
# 13. try/except in a loop
@test
def test_try_in_loop(t):
total = 0 @ t[0]
for i in (range @ t[1])(3 @ t[2]) @ t[3]:
try:
if (i @ t[4, 11, 20] == 1 @ t[5, 12, 21]) @ t[6, 13, 22]:
raise ((ValueError @ t[14])() @ t[15])
total = (total @ t[7, 23] + 1 @ t[8, 24]) @ t[9, 25]
except ValueError:
total = (total @ t[16] + 10 @ t[17]) @ t[18]
r = 0 @ t[10, 19, 26]
# 14. Re-raise with bare `raise`
@test
def test_reraise(t):
try:
try:
x = 1 @ t[0]
raise ((ValueError @ t[1])() @ t[2])
except ValueError:
y = 2 @ t[3]
raise
except ValueError:
z = 3 @ t[4]
after = 0 @ t[5]

View File

@@ -0,0 +1,48 @@
"""Unpacking and star expressions evaluation order."""
from timer import test
@test
def test_tuple_unpack(t):
"""RHS expression evaluates, then unpacking assigns targets."""
a, b = (1 @ t[0], 2 @ t[1]) @ t[2]
x = (a @ t[3] + b @ t[4]) @ t[5]
@test
def test_list_unpack(t):
"""List unpacking: RHS elements left to right, then unpack."""
[a, b] = [1 @ t[0], 2 @ t[1]] @ t[2]
x = (a @ t[3] + b @ t[4]) @ t[5]
@test
def test_star_unpack(t):
"""Star unpacking: RHS evaluates first."""
a, *b = [1 @ t[0], 2 @ t[1], 3 @ t[2], 4 @ t[3]] @ t[4]
x = (a @ t[5], b @ t[6]) @ t[7]
@test
def test_nested_unpack(t):
"""Nested unpacking: RHS evaluates first."""
(a, b), c = ((1 @ t[0], 2 @ t[1]) @ t[2], 3 @ t[3]) @ t[4]
x = ((a @ t[5] + b @ t[6]) @ t[7] + c @ t[8]) @ t[9]
@test
def test_swap(t):
a = 1 @ t[0]
b = 2 @ t[1]
a, b = (b @ t[2], a @ t[3]) @ t[4]
x = a @ t[5]
y = b @ t[6]
@test
def test_unpack_for(t):
pairs = [(1 @ t[0], 2 @ t[1]) @ t[2], (3 @ t[3], 4 @ t[4]) @ t[5]] @ t[6]
for a, b in pairs @ t[7]:
x = a @ t[8, 10]
y = b @ t[9, 11]

View File

@@ -0,0 +1,58 @@
"""Evaluation order tests for with statements."""
from contextlib import contextmanager
from timer import test
@contextmanager
def ctx(value=None):
yield value
@test
def test_simple_with(t):
x = 1 @ t[0]
with (ctx @ t[1])() @ t[2]:
y = 2 @ t[3]
z = 3 @ t[4]
@test
def test_with_as(t):
with (ctx @ t[0])(42 @ t[1]) @ t[2] as v:
x = v @ t[3]
y = 0 @ t[4]
@test
def test_nested_with(t):
with (ctx @ t[0])() @ t[1]:
with (ctx @ t[2])() @ t[3]:
x = 1 @ t[4]
y = 2 @ t[5]
@test
def test_multiple_context_managers(t):
with (ctx @ t[0])(1 @ t[1]) @ t[2] as a, (ctx @ t[3])(2 @ t[4]) @ t[5] as b:
x = (a @ t[6], b @ t[7]) @ t[8]
y = 0 @ t[9]
@test
def test_with_exception_handling(t):
try:
with (ctx @ t[0])() @ t[1]:
x = 1 @ t[2]
raise ((ValueError @ t[3])() @ t[4])
except ValueError:
y = 2 @ t[5]
z = 3 @ t[6]
@test
def test_with_in_loop(t):
for i in [1 @ t[0], 2 @ t[1]] @ t[2]:
with (ctx @ t[3, 6])() @ t[4, 7]:
x = i @ t[5, 8]
y = 0 @ t[9]

View File

@@ -0,0 +1,105 @@
"""Generator and yield evaluation order tests.
Generator bodies are lazy — code runs only when iterated. The timer
annotations inside generator bodies fire interleaved with the caller's
annotations, reflecting the suspend/resume semantics of yield.
"""
from timer import test
@test
def test_simple_generator(t):
"""Basic generator: body runs on next(), not on gen()."""
def gen():
yield 1 @ t[4]
yield 2 @ t[8]
g = (gen @ t[0])() @ t[1]
x = (next @ t[2])(g @ t[3]) @ t[5]
y = (next @ t[6])(g @ t[7]) @ t[9]
@test
def test_multiple_yields(t):
"""Three yields interleave with three next() calls."""
def gen():
yield 1 @ t[4]
yield 2 @ t[8]
yield 3 @ t[12]
g = (gen @ t[0])() @ t[1]
a = (next @ t[2])(g @ t[3]) @ t[5]
b = (next @ t[6])(g @ t[7]) @ t[9]
c = (next @ t[10])(g @ t[11]) @ t[13]
@test
def test_generator_for_loop(t):
"""for-loop consumes generator, interleaving body and loop."""
def gen():
yield 1 @ t[2]
yield 2 @ t[4]
for val in (gen @ t[0])() @ t[1]:
val @ t[3, 5]
@test
def test_generator_list(t):
"""list() consumes the entire generator without interleaving."""
def gen():
yield 10 @ t[3]
yield 20 @ t[4]
yield 30 @ t[5]
result = (list @ t[0])((gen @ t[1])() @ t[2]) @ t[6]
@test
def test_yield_from(t):
"""yield from delegates to an inner generator transparently."""
def inner():
yield 1 @ t[6]
yield 2 @ t[10]
def outer():
yield from (inner @ t[4])() @ t[5]
g = (outer @ t[0])() @ t[1]
x = (next @ t[2])(g @ t[3]) @ t[7]
y = (next @ t[8])(g @ t[9]) @ t[11]
@test
def test_generator_return(t):
"""Generator return value accessed via yield from."""
def gen():
yield 1 @ t[6]
return 42 @ t[10]
def wrapper():
result = (yield from (gen @ t[4])() @ t[5]) @ t[11]
yield result @ t[12]
g = (wrapper @ t[0])() @ t[1]
x = (next @ t[2])(g @ t[3]) @ t[7]
y = (next @ t[8])(g @ t[9]) @ t[13]
@test
def test_generator_send(t):
"""send() passes a value into the generator at the yield point."""
def gen():
x = (yield 1 @ t[4]) @ t[9]
yield (x @ t[10] + 10 @ t[11]) @ t[12]
g = (gen @ t[0])() @ t[1]
first = (next @ t[2])(g @ t[3]) @ t[5]
second = ((g @ t[6]).send @ t[7])(42 @ t[8]) @ t[13]
@test
def test_generator_expression(t):
"""Inline generator expression consumed by list()."""
result = (list @ t[0])(x @ t[5, 6, 7] for x in [10 @ t[1], 20 @ t[2], 30 @ t[3]] @ t[4]) @ t[8]

View File

@@ -0,0 +1,189 @@
"""Abstract timer for self-validating CFG evaluation-order tests.
Provides a Timer context manager and a @test decorator for writing tests
that verify the order in which Python evaluates expressions.
Usage with @test decorator (preferred):
from timer import test, dead, never
@test
def test_sequential(t):
x = 1 @ t[0]
y = 2 @ t[1]
z = (x + y) @ t[2]
Annotation forms:
t[n] - assert current timestamp is n, return marker
t[n, m, ...] - assert current timestamp is one of {n, m, ...}
t[dead(n)] - mark timestamp n as dead (fails if evaluated)
t[dead(n), m] - dead at n, live at m
t[never] - mark as never evaluated (fails if evaluated)
t["label"] - record current timestamp under label (development aid)
t(value, n) - equivalent to: value @ t[n]
Run a test file directly to self-validate: python test_file.py
"""
import atexit
import sys
_results = []
class _Check:
"""Marker returned by t[n] — asserts the current timestamp.
Receives the raw subscript elements: plain ints are live timestamps,
dead(n) markers are dead timestamps, and `never` means any evaluation
is an error.
"""
__slots__ = ("_timer", "_live", "_dead", "_never")
def __init__(self, timer, elements):
self._timer = timer
self._live = set()
self._dead = set()
self._never = False
for e in elements:
if isinstance(e, int):
self._live.add(e)
elif isinstance(e, _DeadMarker):
self._dead.add(e.timestamp)
elif isinstance(e, _NeverSentinel):
self._never = True
def __rmatmul__(self, value):
ts = self._timer._tick()
if self._never:
self._timer._error(
f"expression annotated with t[never] was evaluated (timestamp {ts})"
)
elif ts in self._dead:
self._timer._error(
f"timestamp {ts} is marked dead but was evaluated"
)
elif ts not in self._live:
self._timer._error(
f"expected {sorted(self._live)}, got {ts}"
)
return value
class _Label:
"""Marker returned by t["name"] — records the timestamp under a label."""
__slots__ = ("_timer", "_name")
def __init__(self, timer, name):
self._timer = timer
self._name = name
def __rmatmul__(self, value):
ts = self._timer._tick()
self._timer._labels.setdefault(self._name, []).append(ts)
return value
class _DeadMarker:
"""Marker returned by dead(n) — used inside t[...] to mark a timestamp as dead."""
def __init__(self, timestamp):
self.timestamp = timestamp
def dead(n):
"""Mark timestamp `n` as dead code inside a timer subscript: t[dead(1), 2]."""
return _DeadMarker(n)
class _NeverSentinel:
"""Sentinel for never-evaluated annotations: t[never]."""
pass
never = _NeverSentinel()
class Timer:
"""Context manager tracking abstract evaluation timestamps.
Each Timer instance maintains a counter starting at 0. Every time an
annotation (@ t[n] or t(value, n)) is encountered, the counter is
compared against the expected value and then incremented.
"""
def __init__(self, name="<unnamed>"):
self._name = name
self._counter = 0
self._errors = []
self._labels = {}
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
if self._labels:
for name, timestamps in sorted(self._labels.items()):
print(f" {name}: {', '.join(map(str, timestamps))}")
_results.append((self._name, list(self._errors)))
if self._errors:
print(f"{self._name}: FAIL")
for err in self._errors:
print(f" {err}")
else:
print(f"{self._name}: ok")
return False
def _tick(self):
ts = self._counter
self._counter += 1
return ts
def _error(self, msg):
self._errors.append(msg)
def __getitem__(self, key):
if isinstance(key, str):
return _Label(self, key)
elif isinstance(key, tuple):
return _Check(self, key)
else:
return _Check(self, [key])
def __call__(self, value, key):
"""Alternative to @ operator: t(value, 4) or t(value, [1, 2, 3])."""
if isinstance(key, list):
key = tuple(key)
marker = self[key]
return marker.__rmatmul__(value)
def test(fn):
"""Decorator that creates a Timer and runs the test function immediately.
The function receives a fresh Timer as its sole argument. Errors are
collected (not raised) and reported after the function completes.
"""
with Timer(fn.__name__) as t:
try:
fn(t)
except Exception as e:
t._error(f"exception: {type(e).__name__}: {e}")
return fn
def _report():
"""Print summary at interpreter exit."""
if not _results:
return
total = len(_results)
passed = sum(1 for _, errors in _results if not errors)
print("---")
print(f"{passed}/{total} tests passed")
if passed < total:
sys.exit(1)
atexit.register(_report)