Python: Add copy of extractor tests

These get to live next to the existing library and query tests, and are
run as part of both the Python 2 and Python 3 language tests.

python/ql/test/extractor-tests/pruning/Reachable.expected

@@ -0,0 +1,36 @@
+| 5 | reachable | true |
+| 7 | reachable | true |
+| 11 | reachable | true |
+| 13 | reachable | true |
+| 17 | reachable | true |
+| 19 | reachable | true |
+| 23 | reachable | true |
+| 25 | reachable | true |
+| 29 | reachable | true |
+| 31 | unreachable | false |
+| 35 | reachable | true |
+| 37 | unreachable | false |
+| 41 | reachable | true |
+| 43 | unreachable | false |
+| 47 | reachable | true |
+| 49 | reachable | true |
+| 53 | reachable | true |
+| 55 | unreachable | false |
+| 60 | reachable | true |
+| 62 | reachable | true |
+| 66 | reachable | true |
+| 68 | reachable | true |
+| 72 | reachable | true |
+| 74 | reachable | true |
+| 78 | reachable | true |
+| 80 | reachable | true |
+| 84 | reachable | true |
+| 86 | unreachable | false |
+| 90 | reachable | true |
+| 92 | unreachable | false |
+| 96 | reachable | true |
+| 98 | unreachable | false |
+| 102 | reachable | true |
+| 104 | reachable | true |
+| 108 | reachable | true |
+| 110 | unreachable | false |

python/ql/test/extractor-tests/pruning/Reachable.ql

@@ -0,0 +1,8 @@
+
+import python
+
+from Name n, GlobalVariable v, boolean reachable
+where n.getVariable() = v and exists(ExprStmt s | s.getValue() = n) and
+if exists(ControlFlowNode f | f.getNode() = n) then reachable = true else reachable = false
+
+select n.getLocation().getStartLine(), v.getId(), reachable

python/ql/test/extractor-tests/pruning/Test.expected

@@ -0,0 +1,3 @@
+| comparisons | comparisons.py | 261 |
+| overflow | overflow.py | 18 |
+| plurally_dead_edges | plurally_dead_edges.py | 21 |

python/ql/test/extractor-tests/pruning/Test.ql

@@ -0,0 +1,4 @@
+import python
+
+from Module m
+select m.getName(), m.getFile().getAbsolutePath(), count(ControlFlowNode n | n.getScope().getEnclosingModule() = m)

python/ql/test/extractor-tests/pruning/comparisons.py

@@ -0,0 +1,111 @@
+
+
+def cmp1(x):
+    if x < 3:
+        reachable
+    if x == 0:
+        reachable
+
+def cmp2(x):
+    if x == 0:
+        reachable
+    if x < 3:
+        reachable
+
+def cmp3(x):
+    if x < 3:
+        reachable
+    if x >= 3:
+        reachable
+
+def cmp4(x):
+    if x < 3:
+        reachable
+    if x > 3:
+        reachable
+
+def cmp5(x):
+    if x != 3:
+        reachable
+    elif x > 3:
+        unreachable
+
+def cmp6(x):
+    if x < 3:
+        reachable
+    elif x < 3:
+        unreachable
+
+def cmp7(x):
+    if x < 3:
+        reachable
+    elif x < 2:
+        unreachable
+
+def cmp8(x):
+    if x < 3:
+        reachable
+    elif x == 3:
+        reachable
+
+def cmp9(x):
+    if x < 3:
+        reachable
+    elif x == 2:
+        unreachable
+
+
+def cmp11(x):
+    if x > 3:
+        reachable
+    if x == 0:
+        reachable
+
+def cmp12(x):
+    if x == 0:
+        reachable
+    if x > 3:
+        reachable
+
+def cmp13(x):
+    if x > 3:
+        reachable
+    if x <= 3:
+        reachable
+
+def cmp14(x):
+    if x > 3:
+        reachable
+    if x < 3:
+        reachable
+
+def cmp15(x):
+    if x != 3:
+        reachable
+    elif x < 3:
+        unreachable
+
+def cmp16(x):
+    if x > 3:
+        reachable
+    elif x > 3:
+        unreachable
+
+def cmp17(x):
+    if x > 3:
+        reachable
+    elif x > 4:
+        unreachable
+
+def cmp18(x):
+    if x > 3:
+        reachable
+    elif x == 3:
+        reachable
+
+def cmp19(x):
+    if x > 3:
+        reachable
+    elif x == 4:
+        unreachable
+

python/ql/test/extractor-tests/pruning/overflow.py

@@ -0,0 +1,11 @@
+# -*- coding: utf-8 -*-
+
+
+def func():
+    #Test for overflow in pruning
+    LARGE = 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+    if LARGE:
+        func("Some text")
+    if LARGE:
+        func("Some more text")
+    f = 1

python/ql/test/extractor-tests/pruning/plurally_dead_edges.py

@@ -0,0 +1,17 @@
+# -*- coding: utf-8 -*-
+
+#
+
+class Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx(Yyyyyyyyyyyyyyyyyyyyyyyy):
+
+
+    def ffffffffffffffffffffffff(self, p, ppppppp=20):
+
+        debug = False  # True
+        if debug:
+            print("Some text")
+        if debug:
+            #With splitting, the edge to the print is dead for two different reasons.
+            #But we can only delete it once.
+            print("Some more text")
+        f = 1