TST: Skip tests if message method not implemented

KnownArgumentName tests now skip if the `message` method has not yet been
implemented on `KnownArgumentName` or `KnownDirective` and is required for the
test.

Author: woodb

tests/core_validation/test_known_argument_names.py

@@ -1,3 +1,5 @@
+import pytest
+
 from graphql.core.language.location import SourceLocation
 from graphql.core.validation.rules import KnownArgumentNames, KnownDirectives
 from utils import expect_passes_rule, expect_fails_rule
@@ -82,6 +84,8 @@ def test_directive_args_are_known():
     ''')
 
 
+@pytest.mark.skipif(not hasattr(KnownDirectives, "message"),
+                    reason="KnownDirectives.method() not yet implemented")
 def test_undirective_args_are_invalid():
     expect_fails_rule(KnownArgumentNames, '''
       {
@@ -90,6 +94,8 @@ def test_undirective_args_are_invalid():
     ''', [unknown_directive_arg('unless', 'skip', 3, 19)])
 
 
+@pytest.mark.skipif(not hasattr(KnownArgumentNames, "message"),
+                    reason="KnownArgumentNames.method() not yet implemented")
 def test_invalid_arg_name():
     expect_fails_rule(KnownArgumentNames, '''
       fragment invalidArgName on Dog {
@@ -98,6 +104,8 @@ def test_invalid_arg_name():
     ''', [unknown_arg('unknown', 'doesKnowCommand', 'Dog', 3, 25)])
 
 
+@pytest.mark.skipif(not hasattr(KnownArgumentNames, "message"),
+                    reason="KnownArgumentNames.method() not yet implemented")
 def test_unknown_args_amongst_known_args():
     expect_fails_rule(KnownArgumentNames, '''
       fragment oneGoodArgOneInvalidArg on Dog {
@@ -107,6 +115,8 @@ def test_unknown_args_amongst_known_args():
           unknown_arg('unknown', 'doesKnowCommand', 'Dog', 3, 55)])
 
 
+@pytest.mark.skipif(not hasattr(KnownArgumentNames, "message"),
+                    reason="KnownArgumentNames.method() not yet implemented")
 def test_unknown_args_deeply():
     expect_fails_rule(KnownArgumentNames, '''
       {