feat(eslint-plugin): [no-base-to-string] add option to ignore tagged templates (typescript-eslint#1763)

susisu · web-flow · commit f5edb9938c33 · 2020-04-12T13:29:14.000-07:00
diff --git a/packages/eslint-plugin/docs/rules/no-base-to-string.md b/packages/eslint-plugin/docs/rules/no-base-to-string.md
@@ -52,6 +52,32 @@ const literalWithToString = {
 `Value: ${literalWithToString}`;
 ```
 
+## Options
+
+The rule accepts an options object with the following properties:
+
+```ts
+type Options = {
+  // if true, interpolated expressions in tagged templates will not be checked
+  ignoreTaggedTemplateExpressions?: boolean;
+};
+
+const defaults = {
+  ignoreTaggedTemplateExpressions: false,
+};
+```
+
+### `ignoreTaggedTemplateExpressions`
+
+This allows to skip checking tagged templates, for cases where the tags do not necessarily stringify interpolated values.
+
+Examples of additional **correct** code for this rule with `{ ignoreTaggedTemplateExpressions: true }`:
+
+```ts
+function tag() {}
+tag`${{}}`;
+```
+
 ## When Not To Use It
 
 If you don't mind `"[object Object]"` in your strings, then you will not need this rule.
diff --git a/packages/eslint-plugin/src/rules/no-base-to-string.ts b/packages/eslint-plugin/src/rules/no-base-to-string.ts
@@ -12,7 +12,14 @@ enum Usefulness {
   Sometimes = 'may',
 }
 
-export default util.createRule({
+type Options = [
+  {
+    ignoreTaggedTemplateExpressions?: boolean;
+  },
+];
+type MessageIds = 'baseToString';
+
+export default util.createRule<Options, MessageIds>({
   name: 'no-base-to-string',
   meta: {
     docs: {
@@ -26,11 +33,22 @@ export default util.createRule({
       baseToString:
         "'{{name}} {{certainty}} evaluate to '[object Object]' when stringified.",
     },
-    schema: [],
+    schema: [
+      {
+        type: 'object',
+        properties: {
+          ignoreTaggedTemplateExpressions: {
+            type: 'boolean',
+            default: false,
+          },
+        },
+        additionalProperties: false,
+      },
+    ],
     type: 'suggestion',
   },
-  defaultOptions: [],
-  create(context) {
+  defaultOptions: [{ ignoreTaggedTemplateExpressions: false }],
+  create(context, [options]) {
     const parserServices = util.getParserServices(context);
     const typeChecker = parserServices.program.getTypeChecker();
 
@@ -110,8 +128,14 @@ export default util.createRule({
         const memberExpr = node.parent as TSESTree.MemberExpression;
         checkExpression(memberExpr.object);
       },
-
       TemplateLiteral(node: TSESTree.TemplateLiteral): void {
+        if (
+          options.ignoreTaggedTemplateExpressions &&
+          node.parent &&
+          node.parent.type === AST_NODE_TYPES.TaggedTemplateExpression
+        ) {
+          return;
+        }
         for (const expression of node.expressions) {
           checkExpression(expression);
         }
diff --git a/packages/eslint-plugin/tests/rules/no-base-to-string.test.ts b/packages/eslint-plugin/tests/rules/no-base-to-string.test.ts
@@ -70,6 +70,17 @@ const literalWithToString = {
     'let _ = {} ^ {};',
     'let _ = {} << {};',
     'let _ = {} >> {};',
+    {
+      code: `
+        function tag() {}
+        tag\`\${{}}\`;
+      `,
+      options: [
+        {
+          ignoreTaggedTemplateExpressions: true,
+        },
+      ],
+    },
   ],
   invalid: [
     {
@@ -84,6 +95,21 @@ const literalWithToString = {
         },
       ],
     },
+    {
+      code: `
+        function tag() {}
+        tag\`\${{}}\`;
+      `,
+      errors: [
+        {
+          data: {
+            certainty: 'will',
+            name: '{}',
+          },
+          messageId: 'baseToString',
+        },
+      ],
+    },
     {
       code: '({}.toString());',
       errors: [
