fix(valid-describe): report on concise-body arrow functions (#863)

Author: jcfranco

docs/rules/valid-describe.md

@@ -43,6 +43,12 @@ describe('myFunction', () => {
     });
   });
 });
+
+// Returning a value from a describe block is not allowed
+describe('myFunction', () =>
+  it('returns a truthy value', () => {
+    expect(myFunction()).toBeTruthy();
+  }));
 ```
 
 The following patterns are not considered warnings:

src/rules/__tests__/valid-describe.test.ts

@@ -36,11 +36,6 @@ ruleTester.run('valid-describe', rule, {
         })
       })
     `,
-    dedent`
-      describe('foo', () =>
-        test('bar', () => {})
-      )
-    `,
     dedent`
       if (hasOwnProperty(obj, key)) {
       }
@@ -196,6 +191,16 @@ ruleTester.run('valid-describe', rule, {
         { messageId: 'unexpectedReturnInDescribe', line: 5, column: 5 },
       ],
     },
+    {
+      code: dedent`
+        describe('foo', () =>
+          test('bar', () => {})
+        )
+      `,
+      errors: [
+        { messageId: 'unexpectedReturnInDescribe', line: 1, column: 17 },
+      ],
+    },
     {
       code: 'describe("foo", done => {})',
       errors: [

src/rules/valid-describe.ts

@@ -84,6 +84,13 @@ export default createRule({
           });
         }
 
+        if (callback.body.type === AST_NODE_TYPES.CallExpression) {
+          context.report({
+            messageId: 'unexpectedReturnInDescribe',
+            node: callback,
+          });
+        }
+
         if (callback.body.type === AST_NODE_TYPES.BlockStatement) {
           callback.body.body.forEach(node => {
             if (node.type === AST_NODE_TYPES.ReturnStatement) {