Python: Add tests to illustrate shortcomings of current tests filter

python/ql/test/library-tests/filters/tests/Filter.expected

@@ -1,3 +1,3 @@
-| Class MyTest |
-| Function test_1 |
-| Function test_2 |
+| test.py:4:1:4:23 | Class MyTest |
+| test.py:6:5:6:21 | Function test_1 |
+| test.py:9:5:9:21 | Function test_2 |

python/ql/test/library-tests/filters/tests/Filter.ql

@@ -2,4 +2,4 @@ import python
 import semmle.python.filters.Tests
 
 from TestScope t
-select t.toString()
+select t

python/ql/test/library-tests/filters/tests/test.py

@@ -1,5 +1,3 @@
-
-
 class TestCase:
     pass
 

python/ql/test/library-tests/filters/tests/test_foo.py

@@ -0,0 +1,4 @@
+# This is running under some unknown framework, but is clearly a test!
+
+def test_foo():
+    assert True

python/ql/test/library-tests/filters/tests/unittest_test.py

@@ -0,0 +1,5 @@
+import unittest
+
+class FooTest(unittest.TestCase):
+    def test_valid(self):
+        pass