Feb 14, 2019 · Feb 5, 2019 · Feb 11, 2019 · Feb 12, 2019 · Feb 13, 2019 · Feb 14, 2019
diff --git a/packages/eslint-plugin/docs/rules/no-empty-interface.md b/packages/eslint-plugin/docs/rules/no-empty-interface.md
 interface Baz extends Foo, Bar {}
 ```

 ### Options

 This rule accepts a single object option with the following default configuration:

 ```json
 {
  "@typescript-eslint/no-empty-interface": [
    "error",
    {
      "allowSingleExtends": false
    }
  ]
 }
 ```

 - `allowSingleExtends: true` will silence warnings about extending a single interface without adding additional members

 ## When Not To Use It

 If you don't care about having empty/meaningless interfaces, then you will not need this rule.
diff --git a/packages/eslint-plugin/src/rules/no-empty-interface.ts b/packages/eslint-plugin/src/rules/no-empty-interface.ts
 import { TSESTree } from '@typescript-eslint/typescript-estree';
 import * as util from '../util';

 export default util.createRule({
 type Options = [
  {
    allowSingleExtends?: boolean;
  }
 ];
 type MessageIds = 'noEmpty' | 'noEmptyWithSuper';

 export default util.createRule<Options, MessageIds>({
  name: 'no-empty-interface',
  meta: {
    type: 'suggestion',
      noEmptyWithSuper:
        'An interface declaring no members is equivalent to its supertype.'
    },
    schema: []
    schema: [
      {
        type: 'object',
        additionalProperties: false,
        properties: {
          allowSingleExtends: {
            type: 'boolean'
          }
        }
      }
    ]
  },
  defaultOptions: [],
  create(context) {
  defaultOptions: [
    {
      allowSingleExtends: false
    }
  ],
  create(context, [{ allowSingleExtends }]) {
    return {
      TSInterfaceDeclaration(node: TSESTree.TSInterfaceDeclaration) {
        if (node.body.body.length !== 0) {
          // interface contains members --> Nothing to report
          return;
        }

            messageId: 'noEmpty'
          });
        } else if (node.extends.length === 1) {
          context.report({
            node: node.id,
            messageId: 'noEmptyWithSuper'
          });
          // interface extends exactly 1 interface --> Report depending on rule setting
          if (allowSingleExtends) {
            return;
          } else {
            context.report({
              node: node.id,
              messageId: 'noEmptyWithSuper'
            });
          }
        }
      }
    };
diff --git a/packages/eslint-plugin/tests/rules/no-empty-interface.test.ts b/packages/eslint-plugin/tests/rules/no-empty-interface.test.ts

 // valid because extending multiple interfaces can be used instead of a union type
 interface Baz extends Foo, Bar {}
        `
        `,
    {
      code: `
 interface Foo {
    name: string;
 }

 interface Bar extends Foo {}
        `,
      options: [{ allowSingleExtends: true }]
    }
  ],
  invalid: [
    {

 interface Bar extends Foo {}
            `,
      options: [{ allowSingleExtends: false }],
      errors: [
        {
          messageId: 'noEmptyWithSuper',
Original file line number	Diff line number	Diff line change
Expand Up		@@ -38,6 +38,23 @@ interface Bar {
		interface Baz extends Foo, Bar {}
		```

		### Options

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		This rule accepts a single object option with the following default configuration:

		```json
		{
		"@typescript-eslint/no-empty-interface": [
		"error",
		{
		"allowSingleExtends": false
		}
		]
		}
		```

		- `allowSingleExtends: true` will silence warnings about extending a single interface without adding additional members

		## When Not To Use It

		If you don't care about having empty/meaningless interfaces, then you will not need this rule.
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -6,7 +6,14 @@
		import { TSESTree } from '@typescript-eslint/typescript-estree';
		import * as util from '../util';

		export default util.createRule({
		type Options = [
		{
		allowSingleExtends?: boolean;
		}
		];
		type MessageIds = 'noEmpty' \| 'noEmptyWithSuper';

		export default util.createRule<Options, MessageIds>({
		name: 'no-empty-interface',
		meta: {
		type: 'suggestion',
Expand All		@@ -21,13 +28,28 @@ export default util.createRule({
		noEmptyWithSuper:
		'An interface declaring no members is equivalent to its supertype.'
		},
		schema: []
		schema: [
		{
		type: 'object',
		additionalProperties: false,
		properties: {
		allowSingleExtends: {
		type: 'boolean'
		}
		}
		}
		]
		},
		defaultOptions: [],
		create(context) {
		defaultOptions: [
		{
		allowSingleExtends: false
		}
		],
		create(context, [{ allowSingleExtends }]) {
		return {
		TSInterfaceDeclaration(node: TSESTree.TSInterfaceDeclaration) {
		if (node.body.body.length !== 0) {
		// interface contains members --> Nothing to report
		return;
		}

Expand All		@@ -37,10 +59,15 @@ export default util.createRule({
		messageId: 'noEmpty'
		});
		} else if (node.extends.length === 1) {
		context.report({
		node: node.id,
		messageId: 'noEmptyWithSuper'
		});
		// interface extends exactly 1 interface --> Report depending on rule setting
		if (allowSingleExtends) {
		return;
		} else {
		context.report({
		node: node.id,
		messageId: 'noEmptyWithSuper'
		});
		}
		}
		}
		};
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -23,7 +23,17 @@ interface Bar {

		// valid because extending multiple interfaces can be used instead of a union type
		interface Baz extends Foo, Bar {}
		`
		`,
		{
		code: `
		interface Foo {
		name: string;
		}

		interface Bar extends Foo {}
		`,
		options: [{ allowSingleExtends: true }]
		}
		],
		invalid: [
		{
Expand DownExpand Up		@@ -54,6 +64,7 @@ interface Foo {

		interface Bar extends Foo {}
		`,
		options: [{ allowSingleExtends: false }],
		errors: [
		{
		messageId: 'noEmptyWithSuper',
Expand Down