From f29d1c9d37b0a9865ec2eeda38ffac6e93fb2d3a Mon Sep 17 00:00:00 2001
From: Gilbert Gilb's <gilbsgilbs@users.noreply.github.com>
Date: Thu, 28 Mar 2019 18:43:00 +0100
Subject: [PATCH] fix(eslint-plugin): Fix `allowExpressions` false positives in
 explicit-function-return-type and incorrect documentation (#388)

Fixes #387
---
 .../rules/explicit-function-return-type.md    |  6 +++--
 .../rules/explicit-function-return-type.ts    | 22 +++++++++----------
 .../explicit-function-return-type.test.ts     | 19 ++++++++++++++++
 3 files changed, 34 insertions(+), 13 deletions(-)

diff --git a/packages/eslint-plugin/docs/rules/explicit-function-return-type.md b/packages/eslint-plugin/docs/rules/explicit-function-return-type.md
index e63d3d351a2..b6f37038aba 100644
--- 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
index 9cb9c983104..0d9f9304d2a 100644
--- 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
index 6786b92f4b1..45ff620d616 100644
--- 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 = () => {};`,