fix(eslint-plugin): Fix allowExpressions false positives in explicit-function-return-type and incorrect documentation (typescript-eslint#388)

gilbsgilbs · bradzacher · commit f29d1c9d37b0 · 2019-03-28T10:43:00.000-07:00
Fixes typescript-eslint#387
diff --git a/packages/eslint-plugin/docs/rules/explicit-function-return-type.md b/packages/eslint-plugin/docs/rules/explicit-function-return-type.md
@@ -62,9 +62,11 @@ class Test {
 The rule accepts an options object with the following properties:
 
 - `allowExpressions` if true, only functions which are part of a declaration will be checked
+- `allowTypedFunctionExpressions` if true, type annotations are also allowed on the variable
+  of a function expression rather than on the function directly.
 
-By default, `allowExpressions: false` is used, meaning all declarations and
-expressions _must_ have a return type.
+By default, `allowExpressions: false` and `allowTypedFunctionExpressions: false` are used,
+meaning all declarations and expressions _must_ have a return type.
 
 ### allowExpressions
 
diff --git a/packages/eslint-plugin/src/rules/explicit-function-return-type.ts b/packages/eslint-plugin/src/rules/explicit-function-return-type.ts
@@ -39,7 +39,7 @@ export default util.createRule<Options, MessageIds>({
   },
   defaultOptions: [
     {
-      allowExpressions: true,
+      allowExpressions: false,
       allowTypedFunctionExpressions: false,
     },
   ],
@@ -88,6 +88,16 @@ export default util.createRule<Options, MessageIds>({
         | TSESTree.FunctionDeclaration
         | TSESTree.FunctionExpression,
     ): void {
+      if (
+        options.allowExpressions &&
+        node.type !== AST_NODE_TYPES.FunctionDeclaration &&
+        node.parent &&
+        node.parent.type !== AST_NODE_TYPES.VariableDeclarator &&
+        node.parent.type !== AST_NODE_TYPES.MethodDefinition
+      ) {
+        return;
+      }
+
       if (
         !node.returnType &&
         node.parent &&
@@ -112,16 +122,6 @@ export default util.createRule<Options, MessageIds>({
         | TSESTree.FunctionDeclaration
         | TSESTree.FunctionExpression,
     ): void {
-      if (
-        options.allowExpressions &&
-        node.type !== AST_NODE_TYPES.ArrowFunctionExpression &&
-        node.parent &&
-        node.parent.type !== AST_NODE_TYPES.VariableDeclarator &&
-        node.parent.type !== AST_NODE_TYPES.MethodDefinition
-      ) {
-        return;
-      }
-
       if (
         options.allowTypedFunctionExpressions &&
         node.parent &&
diff --git a/packages/eslint-plugin/tests/rules/explicit-function-return-type.test.ts b/packages/eslint-plugin/tests/rules/explicit-function-return-type.test.ts
@@ -54,6 +54,7 @@ function test() {
             `,
     },
     {
+      filename: 'test.ts',
       code: `fn(() => {});`,
       options: [
         {
@@ -62,6 +63,7 @@ function test() {
       ],
     },
     {
+      filename: 'test.ts',
       code: `fn(function() {});`,
       options: [
         {
@@ -70,6 +72,7 @@ function test() {
       ],
     },
     {
+      filename: 'test.ts',
       code: `[function() {}, () => {}]`,
       options: [
         {
@@ -78,6 +81,7 @@ function test() {
       ],
     },
     {
+      filename: 'test.ts',
       code: `(function() {});`,
       options: [
         {
@@ -86,6 +90,7 @@ function test() {
       ],
     },
     {
+      filename: 'test.ts',
       code: `(() => {})();`,
       options: [
         {
@@ -193,6 +198,20 @@ class Test {
         },
       ],
     },
+    {
+      filename: 'test.ts',
+      code: `function test() {
+        return;
+      }`,
+      options: [{ allowExpressions: true }],
+      errors: [
+        {
+          messageId: 'missingReturnType',
+          line: 1,
+          column: 1,
+        },
+      ],
+    },
     {
       filename: 'test.ts',
       code: `const foo = () => {};`,

Original file line number	Diff line number	Diff line change
`@@ -54,6 +54,7 @@ function test() {`
`54`	`54`	`,
`55`	`55`	`},`
`56`	`56`	`{`
	`57`	`+ filename: 'test.ts',`
`57`	`58`	code: `fn(() => {});`,
`58`	`59`	`options: [`
`59`	`60`	`{`
`@@ -62,6 +63,7 @@ function test() {`
`62`	`63`	`],`
`63`	`64`	`},`
`64`	`65`	`{`
	`66`	`+ filename: 'test.ts',`
`65`	`67`	code: `fn(function() {});`,
`66`	`68`	`options: [`
`67`	`69`	`{`
`@@ -70,6 +72,7 @@ function test() {`
`70`	`72`	`],`
`71`	`73`	`},`
`72`	`74`	`{`
	`75`	`+ filename: 'test.ts',`
`73`	`76`	code: `[function() {}, () => {}]`,
`74`	`77`	`options: [`
`75`	`78`	`{`
`@@ -78,6 +81,7 @@ function test() {`
`78`	`81`	`],`
`79`	`82`	`},`
`80`	`83`	`{`
	`84`	`+ filename: 'test.ts',`
`81`	`85`	code: `(function() {});`,
`82`	`86`	`options: [`
`83`	`87`	`{`
`@@ -86,6 +90,7 @@ function test() {`
`86`	`90`	`],`
`87`	`91`	`},`
`88`	`92`	`{`
	`93`	`+ filename: 'test.ts',`
`89`	`94`	code: `(() => {})();`,
`90`	`95`	`options: [`
`91`	`96`	`{`
`@@ -193,6 +198,20 @@ class Test {`
`193`	`198`	`},`
`194`	`199`	`],`
`195`	`200`	`},`
	`201`	`+ {`
	`202`	`+ filename: 'test.ts',`
	`203`	+ code: `function test() {
	`204`	`+ return;`
	`205`	+ }`,
	`206`	`+ options: [{ allowExpressions: true }],`
	`207`	`+ errors: [`
	`208`	`+ {`
	`209`	`+ messageId: 'missingReturnType',`
	`210`	`+ line: 1,`
	`211`	`+ column: 1,`
	`212`	`+ },`
	`213`	`+ ],`
	`214`	`+ },`
`196`	`215`	`{`
`197`	`216`	`filename: 'test.ts',`
`198`	`217`	code: `const foo = () => {};`,