From 355b3b436d7fd4334284a1747843599830c47794 Mon Sep 17 00:00:00 2001
From: Simeon Cheeseman <simeon@tablecheck.com>
Date: Tue, 2 Apr 2019 13:18:05 +0900
Subject: [PATCH] feat: support interfaces for delimiter-dangle

fix #381
---
 .README/rules/delimiter-dangle.md         |  4 +++-
 src/rules/delimiterDangle.js              | 16 +++++++++++-----
 tests/rules/assertions/delimiterDangle.js | 14 ++++++++++++++
 3 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/.README/rules/delimiter-dangle.md b/.README/rules/delimiter-dangle.md
index 46eb1445..63282113 100644
--- a/.README/rules/delimiter-dangle.md
+++ b/.README/rules/delimiter-dangle.md
@@ -4,7 +4,9 @@ _The `--fix` option on the command line automatically fixes problems reported by
 
 Enforces consistent use of trailing commas in Object and Tuple annotations.
 
-This rule takes one argument which mirrors ESLint's default `comma-dangle` rule.
+This rule takes two arguments which both mirror ESLint's default `comma-dangle` rule.
+The first argument is for Object and Tuble annotations.
+The second argument is used for Interface annotations as ESLint's default `comma-dangle` doesn't apply to interfaces. 
 
 If it is `'never'` then a problem is raised when there is a trailing comma.
 
diff --git a/src/rules/delimiterDangle.js b/src/rules/delimiterDangle.js
index 7397f5db..2a03939f 100644
--- a/src/rules/delimiterDangle.js
+++ b/src/rules/delimiterDangle.js
@@ -1,6 +1,10 @@
 import _ from 'lodash';
 
 const schema = [
+  {
+    enum: ['always', 'always-multiline', 'only-multiline', 'never'],
+    type: 'string'
+  },
   {
     enum: ['always', 'always-multiline', 'only-multiline', 'never'],
     type: 'string'
@@ -9,6 +13,7 @@ const schema = [
 
 const create = (context) => {
   const option = context.options[0] || 'never';
+  const interfaceOption = context.options[1] || option;
   const sourceCode = context.getSourceCode();
 
   const reporter = (node, message, fix) => {
@@ -43,32 +48,33 @@ const create = (context) => {
     const isMultiLine = penultimateToken.loc.start.line !== lastToken.loc.start.line;
 
     const report = makeReporters(lastChildNode, penultimateToken);
+    const nodeOption = node.parent.type === 'InterfaceDeclaration' ? interfaceOption : option;
 
-    if (option === 'always' && !isDangling) {
+    if (nodeOption === 'always' && !isDangling) {
       report.noDangle();
 
       return;
     }
 
-    if (option === 'never' && isDangling) {
+    if (nodeOption === 'never' && isDangling) {
       report.dangle();
 
       return;
     }
 
-    if (option === 'always-multiline' && !isDangling && isMultiLine) {
+    if (nodeOption === 'always-multiline' && !isDangling && isMultiLine) {
       report.noDangle();
 
       return;
     }
 
-    if (option === 'always-multiline' && isDangling && !isMultiLine) {
+    if (nodeOption === 'always-multiline' && isDangling && !isMultiLine) {
       report.dangle();
 
       return;
     }
 
-    if (option === 'only-multiline' && isDangling && !isMultiLine) {
+    if (nodeOption === 'only-multiline' && isDangling && !isMultiLine) {
       report.dangle();
     }
   };
diff --git a/tests/rules/assertions/delimiterDangle.js b/tests/rules/assertions/delimiterDangle.js
index dd590ea9..460b22dc 100644
--- a/tests/rules/assertions/delimiterDangle.js
+++ b/tests/rules/assertions/delimiterDangle.js
@@ -54,6 +54,14 @@ const OBJECT_TYPE_ANNOTATION = {
       output: 'type X = { foo: string }'
     },
 
+    // interface override
+    {
+      code: 'interface X { foo: string; }',
+      errors: [{message: 'Unexpected trailing delimiter'}],
+      options: ['always', 'never'],
+      output: 'interface X { foo: string }'
+    },
+
     // Only indexers...
     {
       code: 'type X = { [key: string]: number, }',
@@ -269,6 +277,12 @@ const OBJECT_TYPE_ANNOTATION = {
       options: ['only-multiline']
     },
 
+    // interface override
+    {
+      code: 'interface X { foo: string; }',
+      options: ['never', 'always']
+    },
+
     // Empty...
     {
       code: 'type X = {}',