Test run-running dmypy after a file is altered

These tests show how some errors disappear on a re-run of dmypy after a
file is altered.

Author: meshy

test-data/unit/daemon.test

@@ -574,7 +574,7 @@ class B:
 
 [case testUnusedTypeIgnorePreservedOnRerun]
 -- Regression test for https://github.com/python/mypy/issues/9655
-$ dmypy start -- --warn-unused-ignores --no-error-summary
+$ dmypy start -- --warn-unused-ignores --no-error-summary --hide-error-codes
 Daemon started
 $ dmypy check -- bar.py
 bar.py:2: error: Unused "type: ignore" comment
@@ -606,6 +606,42 @@ bar.py:2: error: "type: ignore" comment without error code  [ignore-without-code
 from foo.empty import *
 a = 1  # type: ignore
 
+[case testUnusedTypeIgnorePreservedAfterChange]
+-- Regression test for https://github.com/python/mypy/issues/9655
+$ dmypy start -- --warn-unused-ignores --no-error-summary --hide-error-codes
+Daemon started
+$ dmypy check -- bar.py
+bar.py:2: error: Unused "type: ignore" comment
+== Return code: 1
+$ echo '' >> bar.py
+$ dmypy check -- bar.py
+bar.py:2: error: Unused "type: ignore" comment
+== Return code: 1
+
+[file foo/__init__.py]
+[file foo/empty.py]
+[file bar.py]
+from foo.empty import *
+a = 1  # type: ignore
+
+[case testTypeIgnoreWithoutCodePreservedAfterChange]
+-- Regression test for https://github.com/python/mypy/issues/9655
+$ dmypy start -- --enable-error-code ignore-without-code --no-error-summary
+Daemon started
+$ dmypy check -- bar.py
+bar.py:2: error: "type: ignore" comment without error code  [ignore-without-code]
+== Return code: 1
+$ echo '' >> bar.py
+$ dmypy check -- bar.py
+bar.py:2: error: "type: ignore" comment without error code  [ignore-without-code]
+== Return code: 1
+
+[file foo/__init__.py]
+[file foo/empty.py]
+[file bar.py]
+from foo.empty import *
+a = 1  # type: ignore
+
 [case testPossiblyUndefinedVarsPreservedAfterUpdate]
 -- Regression test for https://github.com/python/mypy/issues/9655
 $ dmypy start -- --enable-error-code possibly-undefined --no-error-summary