tests: Add unit tests for annotations.get_known_future_tags()

tests/data/project7/file1.py

@@ -0,0 +1,2 @@
+# TIMEBOMB: FEWTURE-BOOM1
+# FEWTURE-DO-NOT-REPORT: do not report, it's not within an annotation

tests/data/project7/file2.py

@@ -0,0 +1 @@
+# TIMEBOMB: FEWTURE-BOOM2

tests/test_annotations.py

@@ -3,6 +3,8 @@
 
 from check_oldies import annotations
 
+from . import base
+
 
 FAKE_GIT_BLAME_OUTPUT = """c106813f91ff43b8fc6e231c263bdaa344866157 136 136 1
 some value
@@ -65,3 +67,26 @@ def test_get_login_from_committer_email():
     assert login == "<@example.com>"  # should not be the empty string
     login = annotations.get_login_from_committer_email("John Smith")
     assert login == "John Smith"
+
+
+
+class TestGetKnownFutureTag:
+    test_data_path = base.TEST_DIR_PATH / "data/project7"
+
+    def test_basics(self):
+        tags = annotations.get_known_future_tags(
+            directory=self.test_data_path,
+            annotation_regex=base.TESTING_ANNOTATIONS[0],
+            future_tag_regex=base.TESTING_FUTURE_TAG,
+            whitelist=(),
+        )
+        assert tags == {"FEWTURE-BOOM1", "FEWTURE-BOOM2"}
+
+    def test_whitelist(self):
+        tags = annotations.get_known_future_tags(
+            directory=self.test_data_path,
+            annotation_regex=base.TESTING_ANNOTATIONS[0],
+            future_tag_regex=base.TESTING_FUTURE_TAG,
+            whitelist=["file2.py"],
+        )
+        assert tags == {"FEWTURE-BOOM1"}