Complain if expect is passed multiple arguments (#4237)

jestjs · Aug 10, 2017 · 8a0bdd2 · 8a0bdd2
1 parent e16ce6b
commit 8a0bdd2
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Showing 2 changed files with 11 additions and 1 deletion.
diff --git a/packages/jest-matchers/src/__tests__/matchers.test.js b/packages/jest-matchers/src/__tests__/matchers.test.js
@@ -11,6 +11,12 @@
 const {stringify} = require('jest-matcher-utils');
 const jestExpect = require('../');
 
+it('should throw if passed two arguments', () => {
+  expect(() => jestExpect('foo', 'bar')).toThrow(
+    new Error('Expect takes at most one argument.'),
+  );
+});
+
 describe('.rejects', () => {
   it('should reject', async () => {
     await jestExpect(Promise.reject(4)).rejects.toBe(4);

diff --git a/packages/jest-matchers/src/index.js b/packages/jest-matchers/src/index.js
@@ -52,7 +52,11 @@ const isPromise = obj => {
   );
 };
 
-const expect = (actual: any): ExpectationObject => {
+const expect = (actual: any, ...rest): ExpectationObject => {
+  if (rest.length !== 0) {
+    throw new Error('Expect takes at most one argument.');
+  }
+
   const allMatchers = getMatchers();
   const expectation = {
     not: {},