Targetted flag reset approach for error code tests

Reloading module did not work for mypyc, switch ErrorCode.enabled reset
TypeCheckSuite.run_test_case now checks for flags on enable_error_code
and disable_error_code, iterating through the resulting codes and
resetting each's enabled attribute based on default_enabled

Author: cph-w

mypy/errorcodes.py

@@ -14,11 +14,15 @@
 
 
 class ErrorCode:
-    def __init__(self, code: str, description: str, category: str, enabled: bool = True) -> None:
+    def __init__(self, code: str,
+                 description: str,
+                 category: str,
+                 default_enabled: bool = True) -> None:
         self.code = code
         self.description = description
         self.category = category
-        self.enabled = enabled
+        self.default_enabled = default_enabled
+        self.enabled = default_enabled
         error_codes[code] = self
 
     def __str__(self) -> str:

mypy/main.py

@@ -18,7 +18,7 @@
 from mypy.find_sources import create_source_list, InvalidSourceList
 from mypy.fscache import FileSystemCache
 from mypy.errors import CompileError
-from mypy import errorcodes
+from mypy.errorcodes import error_codes
 from mypy.options import Options, BuildType
 from mypy.config_parser import parse_version, parse_config_file
 from mypy.split_namespace import SplitNamespace
@@ -1017,7 +1017,7 @@ def process_error_codes(codes: Iterable[str], enable: bool) -> List[str]:
 
     # process globally disabled error codes
     for code in codes:
-        as_code = errorcodes.error_codes.get(code)
+        as_code = error_codes.get(code)
         if not as_code:
             invalid_error_codes.append(code)
             continue

mypy/test/testcheck.py

@@ -1,6 +1,5 @@
 """Type checker test cases"""
 
-import importlib
 import os
 import re
 import sys
@@ -55,7 +54,6 @@
     'check-type-promotion.test',
     'check-semanal-error.test',
     'check-flags.test',
-    'check-errorcode-flags.test',
     'check-incremental.test',
     'check-serialize.test',
     'check-bound.test',
@@ -258,8 +256,12 @@ def run_case_once(self, testcase: DataDrivenTestCase,
 
         # Post run cleanup step to reset the state of the ErrorCodes that may
         # have been enabled or disabled by flags
-        if 'errorcode-flags' in testcase.file:
-            importlib.reload(errorcodes)
+        if options.disable_error_code or options.enable_error_code:
+            altered_error_codes = set(
+                options.disable_error_code).union(set(options.enable_error_code))
+            for code in altered_error_codes:
+                error_code = errorcodes.error_codes[code]
+                error_code.enabled = error_code.default_enabled
 
     def verify_cache(self, module_data: List[Tuple[str, str, str]], a: List[str],
                      manager: build.BuildManager, graph: Graph) -> None:

test-data/unit/check-errorcode-flags.test

@@ -1501,3 +1501,48 @@ class ShouldNotBeFine(x): ...  # E: Class cannot subclass 'x' (has type 'Any')
 disallow_subclassing_any = True
 \[mypy-m]
 disallow_subclassing_any = False
+
+[case testDisableErrorCode]
+# flags: --disable-error-code attr-defined
+x = 'should be fine'
+x.trim()
+
+[case testDisableDifferentErrorCode]
+# flags: --disable-error-code name-defined --show-error-code
+x = 'should not be fine'
+x.trim()  # E: "str" has no attribute "trim"  [attr-defined]
+
+[case testDisableMultipleErrorCode]
+# flags: --disable-error-code attr-defined --disable-error-code return-value --show-error-code
+x = 'should be fine'
+x.trim()
+
+def bad_return_type() -> str:
+    return None
+
+bad_return_type('no args taken!')  # E: Too many arguments for "bad_return_type"  [call-arg]
+
+[case testEnableErrorCode]
+# flags: --disable-error-code attr-defined --enable-error-code attr-defined --show-error-code
+x = 'should be fine'
+x.trim()  # E: "str" has no attribute "trim"  [attr-defined]
+
+[case testEnableDifferentErrorCode]
+# flags: --disable-error-code attr-defined --enable-error-code name-defined --show-error-code
+x = 'should not be fine'
+x.trim()  # E: "str" has no attribute "trim"  [attr-defined]
+
+[case testEnableMultipleErrorCode]
+# flags: \
+    --disable-error-code attr-defined \
+    --disable-error-code return-value \
+    --disable-error-code call-arg \
+    --enable-error-code attr-defined \
+    --enable-error-code return-value --show-error-code
+x = 'should be fine'
+x.trim()  # E: "str" has no attribute "trim"  [attr-defined]
+
+def bad_return_type() -> str:
+    return None  # E: Incompatible return value type (got "None", expected "str")  [return-value]
+
+bad_return_type('no args taken!')