fix(valid-title): ignore string addition (#461)

Author: G-Rath

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

@@ -12,6 +12,8 @@ const ruleTester = new TSESLint.RuleTester({
 ruleTester.run('title-must-be-string', rule, {
   valid: [
     'it("is a string", () => {});',
+    'it("is" + " a " + " string", () => {});',
+    'it(1 + " + " + 1, () => {});',
     'test("is a string", () => {});',
     'xtest("is a string", () => {});',
     'xtest(`${myFunc} is a string`, () => {});',
@@ -53,6 +55,16 @@ ruleTester.run('title-must-be-string', rule, {
         },
       ],
     },
+    {
+      code: 'it(1 + 2 + 3, () => {});',
+      errors: [
+        {
+          messageId: 'titleMustBeString',
+          column: 4,
+          line: 1,
+        },
+      ],
+    },
     {
       code: 'test.skip(123, () => {});',
       options: [{ ignoreTypeOfDescribeName: true }],

src/rules/valid-title.ts

@@ -17,6 +17,20 @@ import {
 const trimFXprefix = (word: string) =>
   ['f', 'x'].includes(word.charAt(0)) ? word.substr(1) : word;
 
+const doesBinaryExpressionContainStringNode = (
+  binaryExp: TSESTree.BinaryExpression,
+): boolean => {
+  if (isStringNode(binaryExp.right)) {
+    return true;
+  }
+
+  if (binaryExp.left.type === AST_NODE_TYPES.BinaryExpression) {
+    return doesBinaryExpressionContainStringNode(binaryExp.left);
+  }
+
+  return isStringNode(binaryExp.left);
+};
+
 export default createRule({
   name: __filename,
   meta: {
@@ -57,6 +71,13 @@ export default createRule({
         const [argument] = getJestFunctionArguments(node);
 
         if (!isStringNode(argument)) {
+          if (
+            argument.type === AST_NODE_TYPES.BinaryExpression &&
+            doesBinaryExpressionContainStringNode(argument)
+          ) {
+            return;
+          }
+
           if (
             argument.type !== AST_NODE_TYPES.TemplateLiteral &&
             !(ignoreTypeOfDescribeName && isDescribe(node))