Python: Add API graph test for calling coroutines

Author: RasmusWL

python/ql/test/experimental/dataflow/ApiGraphs/async_test.py

@@ -0,0 +1,17 @@
+import pkg # $ use=moduleImport("pkg")
+
+async def foo():
+    coro = pkg.async_func() # $ use=moduleImport("pkg").getMember("async_func").getReturn()
+    coro # $ use=moduleImport("pkg").getMember("async_func").getReturn()
+    result = await coro # $ use=moduleImport("pkg").getMember("async_func").getReturn()
+    result # $ MISSING: use=...
+    return result # $ MISSING: use=...
+
+async def bar():
+    result = await pkg.async_func() # $ use=moduleImport("pkg").getMember("async_func").getReturn()
+    return result # $ MISSING: use=...
+
+def check_annotations():
+    # Just to make sure how annotations should look like :)
+    result = pkg.sync_func() # $ use=moduleImport("pkg").getMember("sync_func").getReturn()
+    return result # $ use=moduleImport("pkg").getMember("sync_func").getReturn()