fix(eslint-plugin): [member-delimiter-style] correct invalid fix for multiline with params on the same line

packages/eslint-plugin/src/rules/member-delimiter-style.ts

@@ -1,4 +1,5 @@
 import {
+  TSESLint,
   TSESTree,
   AST_NODE_TYPES,
 } from '@typescript-eslint/experimental-utils';
@@ -11,6 +12,9 @@ type TypeOptions = {
   delimiter?: Delimiter;
   requireLast?: boolean;
 };
+type TypeOptionsWithType = TypeOptions & {
+  type: string;
+};
 // eslint-disable-next-line @typescript-eslint/consistent-type-definitions
 type BaseOptions = {
   multiline?: TypeOptions;
@@ -29,6 +33,20 @@ type MessageIds =
   | 'unexpectedSemi'
   | 'expectedComma'
   | 'expectedSemi';
+type LastTokenType = TSESTree.Token;
+
+interface MakeFixFunctionParams {
+  optsNone: boolean;
+  optsSemi: boolean;
+  lastToken: LastTokenType;
+  missingDelimiter: boolean;
+  lastTokenLine: string;
+  isSingleLine: boolean;
+}
+
+type MakeFixFunctionReturnType =
+  | ((fixer: TSESLint.RuleFixer) => TSESLint.RuleFix)
+  | null;
 
 const definition = {
   type: 'object',
@@ -54,6 +72,47 @@ const definition = {
   additionalProperties: false,
 };
 
+const isLastTokenEndOfLine = (token: string, line: string): boolean => {
+  const positionInLine = line.indexOf(token);
+
+  return positionInLine === line.length - 1;
+};
+
+const makeFixFunction = ({
+  optsNone,
+  optsSemi,
+  lastToken,
+  missingDelimiter,
+  lastTokenLine,
+  isSingleLine,
+}: MakeFixFunctionParams): MakeFixFunctionReturnType => {
+  // if removing is the action but last token is not the end of the line
+  if (
+    optsNone &&
+    !isLastTokenEndOfLine(lastToken.value, lastTokenLine) &&
+    !isSingleLine
+  ) {
+    return null;
+  }
+
+  return (fixer: TSESLint.RuleFixer): TSESLint.RuleFix => {
+    if (optsNone) {
+      // remove the unneeded token
+      return fixer.remove(lastToken);
+    }
+
+    const token = optsSemi ? ';' : ',';
+
+    if (missingDelimiter) {
+      // add the missing delimiter
+      return fixer.insertTextAfter(lastToken, token);
+    }
+
+    // correct the current delimiter
+    return fixer.replaceText(lastToken, token);
+  };
+};
+
 export default util.createRule<Options, MessageIds>({
   name: 'member-delimiter-style',
   meta: {
@@ -127,7 +186,7 @@ export default util.createRule<Options, MessageIds>({
      */
     function checkLastToken(
       member: TSESTree.TypeElement,
-      opts: TypeOptions,
+      opts: TypeOptionsWithType,
       isLast: boolean,
     ): void {
       /**
@@ -147,10 +206,14 @@ export default util.createRule<Options, MessageIds>({
       const lastToken = sourceCode.getLastToken(member, {
         includeComments: false,
       });
+
       if (!lastToken) {
         return;
       }
 
+      const sourceCodeLines = sourceCode.getLines();
+      const lastTokenLine = sourceCodeLines[lastToken?.loc.start.line - 1];
+
       const optsSemi = getOption('semi');
       const optsComma = getOption('comma');
       const optsNone = getOption('none');
@@ -193,22 +256,14 @@ export default util.createRule<Options, MessageIds>({
             },
           },
           messageId,
-          fix(fixer) {
-            if (optsNone) {
-              // remove the unneeded token
-              return fixer.remove(lastToken);
-            }
-
-            const token = optsSemi ? ';' : ',';
-
-            if (missingDelimiter) {
-              // add the missing delimiter
-              return fixer.insertTextAfter(lastToken, token);
-            }
-
-            // correct the current delimiter
-            return fixer.replaceText(lastToken, token);
-          },
+          fix: makeFixFunction({
+            optsNone,
+            optsSemi,
+            lastToken,
+            missingDelimiter,
+            lastTokenLine,
+            isSingleLine: opts.type === 'single-line',
+          }),
         });
       }
     }
@@ -239,7 +294,9 @@ export default util.createRule<Options, MessageIds>({
         node.type === AST_NODE_TYPES.TSInterfaceBody
           ? interfaceOptions
           : typeLiteralOptions;
-      const opts = isSingleLine ? typeOpts.singleline : typeOpts.multiline;
+      const opts = isSingleLine
+        ? { ...typeOpts.singleline, type: 'single-line' }
+        : { ...typeOpts.multiline, type: 'multi-line' };
 
       members.forEach((member, index) => {
         checkLastToken(member, opts ?? {}, index === members.length - 1);

packages/eslint-plugin/tests/rules/member-delimiter-style.test.ts

@@ -851,6 +851,24 @@ interface Foo {
     },
     {
       code: `
+type Test = {
+  a: {
+      one: 1
+  }; b: 2
+};
+      `,
+      output: null,
+      options: [{ multiline: { delimiter: 'none' } }],
+      errors: [
+        {
+          messageId: 'unexpectedSemi',
+          line: 5,
+          column: 5,
+        },
+      ],
+    },
+    {
+      code: `
 interface Foo {
     name: string
     age: number