Better support valid each (#460)

* chore(utils): create `getJestFunctionArguments` utility function

* fix(valid-describe): better support `.each` function

* fix(valid-title): better support `.each` function

Author: G-Rath

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

@@ -11,16 +11,11 @@ const ruleTester = new TSESLint.RuleTester({
 
 ruleTester.run('valid-describe', rule, {
   valid: [
-    'describe.each()()',
-    'describe.each(() => {})()',
     'describe["each"]()()',
     'describe["each"](() => {})()',
     'describe["each"](() => {})("foo")',
-    'describe.each(() => {})("foo")',
     'describe["each"]()(() => {})',
-    'describe.each()(() => {})',
     'describe["each"]("foo")(() => {})',
-    'describe.each("foo")(() => {})',
     'describe("foo", function() {})',
     'describe("foo", () => {})',
     'describe(`foo`, () => {})',
@@ -55,6 +50,26 @@ ruleTester.run('valid-describe', rule, {
     `,
   ],
   invalid: [
+    {
+      code: 'describe.each()()',
+      errors: [{ messageId: 'nameAndCallback', line: 1, column: 1 }],
+    },
+    {
+      code: 'describe.each(() => {})()',
+      errors: [{ messageId: 'nameAndCallback', line: 1, column: 1 }],
+    },
+    {
+      code: 'describe.each(() => {})("foo")',
+      errors: [{ messageId: 'nameAndCallback', line: 1, column: 25 }],
+    },
+    {
+      code: 'describe.each()(() => {})',
+      errors: [{ messageId: 'nameAndCallback', line: 1, column: 17 }],
+    },
+    {
+      code: 'describe.each("foo")(() => {})',
+      errors: [{ messageId: 'nameAndCallback', line: 1, column: 22 }],
+    },
     {
       code: 'describe(() => {})',
       errors: [{ messageId: 'nameAndCallback', line: 1, column: 10 }],

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

@@ -33,6 +33,16 @@ ruleTester.run('title-must-be-string', rule, {
     },
   ],
   invalid: [
+    {
+      code: 'it.each([])(1, () => {});',
+      errors: [
+        {
+          messageId: 'titleMustBeString',
+          column: 13,
+          line: 1,
+        },
+      ],
+    },
     {
       code: 'it(123, () => {});',
       errors: [

src/rules/utils.ts

@@ -651,6 +651,26 @@ export const isDescribe = (
   );
 };
 
+/**
+ * Gets the arguments of the given `JestFunctionCallExpression`.
+ *
+ * If the `node` is an `each` call, then the arguments of the actual suite
+ * are returned, rather then the `each` array argument.
+ *
+ * @param {JestFunctionCallExpression<DescribeAlias | TestCaseName>} node
+ *
+ * @return {Expression[]}
+ */
+export const getJestFunctionArguments = (
+  node: JestFunctionCallExpression<DescribeAlias | TestCaseName>,
+) =>
+  node.callee.type === AST_NODE_TYPES.MemberExpression &&
+  isSupportedAccessor(node.callee.property, DescribeProperty.each) &&
+  node.parent &&
+  node.parent.type === AST_NODE_TYPES.CallExpression
+    ? node.parent.arguments
+    : node.arguments;
+
 const collectReferences = (scope: TSESLint.Scope.Scope) => {
   const locals = new Set();
   const unresolved = new Set();

src/rules/valid-describe.ts

@@ -4,9 +4,9 @@ import {
 } from '@typescript-eslint/experimental-utils';
 import {
   createRule,
+  getJestFunctionArguments,
   isDescribe,
   isFunction,
-  isSupportedAccessor,
 } from './utils';
 
 const paramsLocation = (
@@ -21,10 +21,6 @@ const paramsLocation = (
   };
 };
 
-const isDescribeEach = (node: TSESTree.CallExpression) =>
-  node.callee.type === AST_NODE_TYPES.MemberExpression &&
-  isSupportedAccessor(node.callee.property, 'each');
-
 export default createRule({
   name: __filename,
   meta: {
@@ -49,23 +45,25 @@ export default createRule({
   create(context) {
     return {
       CallExpression(node) {
-        if (!isDescribe(node) || isDescribeEach(node)) {
+        if (!isDescribe(node)) {
           return;
         }
 
-        if (node.arguments.length < 1) {
+        const nodeArguments = getJestFunctionArguments(node);
+
+        if (nodeArguments.length < 1) {
           return context.report({
             messageId: 'nameAndCallback',
             loc: node.loc,
           });
         }
 
-        const [, callback] = node.arguments;
+        const [, callback] = nodeArguments;
 
         if (!callback) {
           context.report({
             messageId: 'nameAndCallback',
-            loc: paramsLocation(node.arguments),
+            loc: paramsLocation(nodeArguments),
           });
 
           return;
@@ -74,7 +72,7 @@ export default createRule({
         if (!isFunction(callback)) {
           context.report({
             messageId: 'secondArgumentMustBeFunction',
-            loc: paramsLocation(node.arguments),
+            loc: paramsLocation(nodeArguments),
           });
 
           return;

src/rules/valid-title.ts

@@ -6,6 +6,7 @@ import {
   DescribeAlias,
   TestCaseName,
   createRule,
+  getJestFunctionArguments,
   getNodeName,
   getStringValue,
   isDescribe,
@@ -53,7 +54,7 @@ export default createRule({
           return;
         }
 
-        const [argument] = node.arguments;
+        const [argument] = getJestFunctionArguments(node);
 
         if (!isStringNode(argument)) {
           if (