Python: Add QL test for comprehensions with unpacking

Author: tausbn

python/ql/test/3/extractor-tests/unpacking-comprehensions/test.expected

@@ -0,0 +1,4 @@
+| 3 | ListComp |
+| 5 | SetComp |
+| 7 | DictComp |
+| 9 | GeneratorExp |

python/ql/test/3/extractor-tests/unpacking-comprehensions/test.py

@@ -0,0 +1,12 @@
+# PEP 798: Unpacking in comprehensions
+
+flat_list = [*x for x in nested]
+
+flat_set = {*x for x in nested}
+
+merged = {**d for d in dicts}
+
+gen = (*x for x in nested)
+
+# Force the new parser (the old parser cannot handle lazy imports)
+lazy import _pep798_parser_hint

python/ql/test/3/extractor-tests/unpacking-comprehensions/test.ql

@@ -0,0 +1,12 @@
+import python
+
+from Expr e
+where
+  e.getLocation().getFile().getShortName() = "test.py" and
+  (
+    e instanceof ListComp or
+    e instanceof SetComp or
+    e instanceof DictComp or
+    e instanceof GeneratorExp
+  )
+select e.getLocation().getStartLine(), e.toString()