Python: Support debugging inline taint tests

The module `Conf` is created so that it can be imported
without importing the query predicates from the same file.

python/ql/test/experimental/meta/InlineTaintTest.qll

@@ -30,30 +30,34 @@ DataFlow::Node shouldNotBeTainted() {
   )
 }
 
-class TestTaintTrackingConfiguration extends TaintTracking::Configuration {
-  TestTaintTrackingConfiguration() { this = "TestTaintTrackingConfiguration" }
+module Conf {
+  class TestTaintTrackingConfiguration extends TaintTracking::Configuration {
+    TestTaintTrackingConfiguration() { this = "TestTaintTrackingConfiguration" }
 
-  override predicate isSource(DataFlow::Node source) {
-    source.asCfgNode().(NameNode).getId() in [
-        "TAINTED_STRING", "TAINTED_BYTES", "TAINTED_LIST", "TAINTED_DICT"
-      ]
-    or
-    // User defined sources
-    exists(CallNode call |
-      call.getFunction().(NameNode).getId() = "taint" and
-      source.(DataFlow::CfgNode).getNode() = call.getAnArg()
-    )
-    or
-    source instanceof RemoteFlowSource
-  }
+    override predicate isSource(DataFlow::Node source) {
+      source.asCfgNode().(NameNode).getId() in [
+          "TAINTED_STRING", "TAINTED_BYTES", "TAINTED_LIST", "TAINTED_DICT"
+        ]
+      or
+      // User defined sources
+      exists(CallNode call |
+        call.getFunction().(NameNode).getId() = "taint" and
+        source.(DataFlow::CfgNode).getNode() = call.getAnArg()
+      )
+      or
+      source instanceof RemoteFlowSource
+    }
 
-  override predicate isSink(DataFlow::Node sink) {
-    sink = shouldBeTainted()
-    or
-    sink = shouldNotBeTainted()
+    override predicate isSink(DataFlow::Node sink) {
+      sink = shouldBeTainted()
+      or
+      sink = shouldNotBeTainted()
+    }
   }
 }
 
+import Conf
+
 class InlineTaintTest extends InlineExpectationsTest {
   InlineTaintTest() { this = "InlineTaintTest" }
 

python/ql/test/experimental/meta/debug/InlineTaintTestPaths.expected

@@ -0,0 +1,4 @@
+edges
+nodes
+subpaths
+#select

python/ql/test/experimental/meta/debug/InlineTaintTestPaths.ql

@@ -0,0 +1,25 @@
+/**
+ * @kind path-problem
+ */
+
+// This query is for debugging InlineTaintTestFailures.
+// The intended usage is
+// 1. load the database of the failing test
+// 2. run this query to see actual paths
+// 3. if necessary, look at partial paths by (un)commenting appropriate lines
+import python
+import semmle.python.dataflow.new.DataFlow
+import experimental.meta.InlineTaintTest::Conf
+// import DataFlow::PartialPathGraph
+import DataFlow::PathGraph
+
+class Conf extends TestTaintTrackingConfiguration {
+  override int explorationLimit() { result = 5 }
+}
+
+// from Conf config, DataFlow::PartialPathNode source, DataFlow::PartialPathNode sink
+// where config.hasPartialFlow(source, sink, _)
+from Conf config, DataFlow::PathNode source, DataFlow::PathNode sink
+where config.hasFlowPath(source, sink)
+select sink.getNode(), source, sink, "This node receives taint from $@.", source.getNode(),
+  "this source"