Add 'UniqueArgumentDefinitionNamesRule' validation rule

src/index.ts

@@ -357,6 +357,7 @@ export {
   UniqueTypeNamesRule,
   UniqueEnumValueNamesRule,
   UniqueFieldDefinitionNamesRule,
+  UniqueArgumentDefinitionNamesRule,
   UniqueDirectiveNamesRule,
   PossibleTypeExtensionsRule,
   /** Custom validation rules */

src/validation/__tests__/UniqueArgumentDefinitionNamesRule-test.ts

@@ -0,0 +1,120 @@
+import { describe, it } from 'mocha';
+
+import { UniqueArgumentDefinitionNamesRule } from '../rules/UniqueArgumentDefinitionNamesRule';
+
+import { expectSDLValidationErrors } from './harness';
+
+function expectSDLErrors(sdlStr: string) {
+  return expectSDLValidationErrors(
+    undefined,
+    UniqueArgumentDefinitionNamesRule,
+    sdlStr,
+  );
+}
+
+function expectValidSDL(sdlStr: string) {
+  expectSDLErrors(sdlStr).to.deep.equal([]);
+}
+
+describe('Validate: Unique argument definition names', () => {
+  it('no args', () => {
+    expectValidSDL(`
+      type SomeObject {
+        someField: String
+      }
+
+      interface SomeInterface {
+        someField: String
+      }
+
+      directive @someDirective on QUERY
+    `);
+  });
+
+  it('one argument', () => {
+    expectValidSDL(`
+      type SomeObject {
+        someField(foo: String): String
+      }
+
+      interface SomeInterface {
+        someField(foo: String): String
+      }
+
+      directive @someDirective(foo: String) on QUERY
+    `);
+  });
+
+  it('multiple arguments', () => {
+    expectValidSDL(`
+      type SomeObject {
+        someField(
+          foo: String
+          bar: String
+        ): String
+      }
+
+      interface SomeInterface {
+        someField(
+          foo: String
+          bar: String
+        ): String
+      }
+
+      directive @someDirective(
+        foo: String
+        bar: String
+      ) on QUERY
+    `);
+  });
+
+  it('duplicating arguments', () => {
+    expectSDLErrors(`
+      type SomeObject {
+        someField(
+          foo: String
+          bar: String
+          foo: String
+        ): String
+      }
+
+      interface SomeInterface {
+        someField(
+          foo: String
+          bar: String
+          foo: String
+        ): String
+      }
+
+      directive @someDirective(
+        foo: String
+        bar: String
+        foo: String
+      ) on QUERY
+    `).to.deep.equal([
+      {
+        message:
+          'Argument "SomeObject.someField(foo:)" can only be defined once.',
+        locations: [
+          { line: 4, column: 11 },
+          { line: 6, column: 11 },
+        ],
+      },
+      {
+        message:
+          'Argument "SomeInterface.someField(foo:)" can only be defined once.',
+        locations: [
+          { line: 12, column: 11 },
+          { line: 14, column: 11 },
+        ],
+      },
+      {
+        message: 'Argument "@someDirective(foo:)" can only be defined once.',
+        locations: [
+          { line: 19, column: 9 },
+          { line: 21, column: 9 },
+        ],
+      },
+    ]);
+  });
+});

src/validation/index.ts

@@ -90,6 +90,7 @@ export { UniqueOperationTypesRule } from './rules/UniqueOperationTypesRule';
 export { UniqueTypeNamesRule } from './rules/UniqueTypeNamesRule';
 export { UniqueEnumValueNamesRule } from './rules/UniqueEnumValueNamesRule';
 export { UniqueFieldDefinitionNamesRule } from './rules/UniqueFieldDefinitionNamesRule';
+export { UniqueArgumentDefinitionNamesRule } from './rules/UniqueArgumentDefinitionNamesRule';
 export { UniqueDirectiveNamesRule } from './rules/UniqueDirectiveNamesRule';
 export { PossibleTypeExtensionsRule } from './rules/PossibleTypeExtensionsRule';
 

src/validation/rules/UniqueArgumentDefinitionNamesRule.ts

@@ -0,0 +1,91 @@
+import { GraphQLError } from '../../error/GraphQLError';
+
+import type { ASTVisitor } from '../../language/visitor';
+import type {
+  NameNode,
+  FieldDefinitionNode,
+  InputValueDefinitionNode,
+} from '../../language/ast';
+
+import type { SDLValidationContext } from '../ValidationContext';
+
+/**
+ * Unique argument definition names
+ *
+ * A GraphQL Object or Interface type is only valid if all its fields have uniquely named arguments.
+ * A GraphQL Directive is only valid if all its arguments are uniquely named.
+ */
+export function UniqueArgumentDefinitionNamesRule(
+  context: SDLValidationContext,
+): ASTVisitor {
+  return {
+    DirectiveDefinition(directiveNode) {
+      // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2203')
+      const argumentNodes = directiveNode.arguments ?? [];
+
+      return checkArgUniqueness(`@${directiveNode.name.value}`, argumentNodes);
+    },
+    InterfaceTypeDefinition: checkArgUniquenessPerField,
+    InterfaceTypeExtension: checkArgUniquenessPerField,
+    ObjectTypeDefinition: checkArgUniquenessPerField,
+    ObjectTypeExtension: checkArgUniquenessPerField,
+  };
+
+  function checkArgUniquenessPerField(typeNode: {
+    readonly name: NameNode;
+    readonly fields?: ReadonlyArray<FieldDefinitionNode>;
+  }) {
+    const typeName = typeNode.name.value;
+
+    // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2203')
+    const fieldNodes = typeNode.fields ?? [];
+
+    for (const fieldDef of fieldNodes) {
+      const fieldName = fieldDef.name.value;
+
+      // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2203')
+      const argumentNodes = fieldDef.arguments ?? [];
+
+      checkArgUniqueness(`${typeName}.${fieldName}`, argumentNodes);
+    }
+
+    return false;
+  }
+
+  function checkArgUniqueness(
+    parentName: string,
+    argumentNodes: ReadonlyArray<InputValueDefinitionNode>,
+  ) {
+    const seenArgs = groupBy(argumentNodes, (arg) => arg.name.value);
+
+    for (const [argName, argNodes] of seenArgs) {
+      if (argNodes.length > 1) {
+        context.reportError(
+          new GraphQLError(
+            `Argument "${parentName}(${argName}:)" can only be defined once.`,
+            argNodes.map((node) => node.name),
+          ),
+        );
+      }
+    }
+
+    return false;
+  }
+}
+
+function groupBy<K, T>(
+  list: ReadonlyArray<T>,
+  keyFn: (item: T) => K,
+): Map<K, Array<T>> {
+  const result = new Map<K, Array<T>>();
+  for (const item of list) {
+    const key = keyFn(item);
+    const group = result.get(key);
+    if (group === undefined) {
+      result.set(key, [item]);
+    } else {
+      group.push(item);
+    }
+  }
+  return result;
+}

src/validation/specifiedRules.ts

@@ -90,6 +90,7 @@ import { UniqueOperationTypesRule } from './rules/UniqueOperationTypesRule';
 import { UniqueTypeNamesRule } from './rules/UniqueTypeNamesRule';
 import { UniqueEnumValueNamesRule } from './rules/UniqueEnumValueNamesRule';
 import { UniqueFieldDefinitionNamesRule } from './rules/UniqueFieldDefinitionNamesRule';
+import { UniqueArgumentDefinitionNamesRule } from './rules/UniqueArgumentDefinitionNamesRule';
 import { UniqueDirectiveNamesRule } from './rules/UniqueDirectiveNamesRule';
 import { PossibleTypeExtensionsRule } from './rules/PossibleTypeExtensionsRule';
 
@@ -138,6 +139,7 @@ export const specifiedSDLRules: ReadonlyArray<SDLValidationRule> =
     UniqueTypeNamesRule,
     UniqueEnumValueNamesRule,
     UniqueFieldDefinitionNamesRule,
+    UniqueArgumentDefinitionNamesRule,
     UniqueDirectiveNamesRule,
     KnownTypeNamesRule,
     KnownDirectivesRule,