NEW RULE: avoid-typename-prefix

Author: dotansimha

.changeset/grumpy-tables-drum.md

@@ -0,0 +1,5 @@
+---
+'@graphql-eslint/eslint-plugin': minor
+---
+
+NEW RULE: avoid-typename-prefix

packages/plugin/src/rules/avoid-typename-prefix.ts

@@ -0,0 +1,81 @@
+import { FieldDefinitionNode } from 'graphql';
+import { GraphQLESTreeNode } from '../estree-parser';
+import { GraphQLESLintRule, GraphQLESlintRuleContext } from '../types';
+
+const AVOID_TYPENAME_PREFIX = 'AVOID_TYPENAME_PREFIX';
+
+function checkNode(
+  context: GraphQLESlintRuleContext<any>,
+  typeName: string,
+  fields: GraphQLESTreeNode<FieldDefinitionNode>[]
+) {
+  const lowerTypeName = (typeName || '').toLowerCase();
+
+  for (const field of fields) {
+    const fieldName = field.name.value || '';
+
+    if (fieldName && lowerTypeName && fieldName.toLowerCase().startsWith(lowerTypeName)) {
+      context.report({
+        node: field.name,
+        data: {
+          fieldName,
+          typeName,
+        },
+        messageId: AVOID_TYPENAME_PREFIX,
+      });
+    }
+  }
+}
+
+const rule: GraphQLESLintRule = {
+  meta: {
+    type: 'suggestion',
+    docs: {
+      category: 'Best Practices',
+      description: 'Enforces users to avoid using the type name in a field name while defining your schema.',
+      recommended: true,
+      url: 'https://github.com/dotansimha/graphql-eslint/blob/master/docs/rules/avoid-typename-prefix.md',
+      requiresSiblings: false,
+      requiresSchema: false,
+      examples: [
+        {
+          title: 'Incorrect',
+          code: /* GraphQL */ `
+            type User {
+              userId: ID!
+            }
+          `,
+        },
+        {
+          title: 'Correct',
+          code: /* GraphQL */ `
+            type User {
+              id: ID!
+            }
+          `,
+        },
+      ],
+    },
+    messages: {
+      [AVOID_TYPENAME_PREFIX]: `Field "{{ fieldName }}" starts with the name of the parent type "{{ typeName }}"`,
+    },
+  },
+  create(context) {
+    return {
+      ObjectTypeDefinition(node) {
+        checkNode(context, node.name.value, node.fields);
+      },
+      ObjectTypeExtension(node) {
+        checkNode(context, node.name.value, node.fields);
+      },
+      InterfaceTypeDefinition(node) {
+        checkNode(context, node.name.value, node.fields);
+      },
+      InterfaceTypeExtension(node) {
+        checkNode(context, node.name.value, node.fields);
+      },
+    };
+  },
+};
+
+export default rule;

packages/plugin/src/rules/index.ts

@@ -16,9 +16,11 @@ import noHashtagDescription from './no-hashtag-description';
 import selectionSetDepth from './selection-set-depth';
 import avoidDuplicateFields from './avoid-duplicate-fields';
 import strictIdInTypes from './strict-id-in-types';
+import avoidTypenamePrefix from './avoid-typename-prefix';
 import { GRAPHQL_JS_VALIDATIONS } from './graphql-js-validation';
 
 export const rules = {
+  'avoid-typename-prefix': avoidTypenamePrefix,
   'no-unreachable-types': noUnreachableTypes,
   'no-deprecated': noDeprecated,
   'unique-fragment-name': uniqueFragmentName,

packages/plugin/tests/avoid-typename-prefix.spec.ts

@@ -0,0 +1,61 @@
+import { GraphQLRuleTester } from '../src/testkit';
+import rule from '../src/rules/avoid-typename-prefix';
+
+const ruleTester = new GraphQLRuleTester();
+
+ruleTester.runGraphQLTests('avoid-typename-prefix', rule, {
+  valid: [
+    {
+      code: /* GraphQL */ `
+        type User {
+          id: ID!
+        }
+      `,
+    },
+    {
+      code: /* GraphQL */ `
+        interface Node {
+          id: ID!
+        }
+      `,
+    },
+    {
+      code: /* GraphQL */ `
+        type User {
+          # eslint-disable-next-line
+          userId: ID!
+        }
+      `,
+    },
+  ],
+  invalid: [
+    {
+      code: /* GraphQL */ `
+        type User {
+          userId: ID!
+        }
+      `,
+      errors: [{ message: 'Field "userId" starts with the name of the parent type "User"' }],
+    },
+    {
+      code: /* GraphQL */ `
+        type User {
+          userId: ID!
+          userName: String!
+        }
+      `,
+      errors: [
+        { message: 'Field "userId" starts with the name of the parent type "User"' },
+        { message: 'Field "userName" starts with the name of the parent type "User"' },
+      ],
+    },
+    {
+      code: /* GraphQL */ `
+        interface Node {
+          nodeId: ID!
+        }
+      `,
+      errors: [{ message: 'Field "nodeId" starts with the name of the parent type "Node"' }],
+    },
+  ],
+});