Do not modify stack trace of JestAssertionError (#4516)

* Do not modify stack trace of JestAssertionError.

* Added test for stack trace of nested matchers.

* Fixed test for nested matcher and added test for normal matchers.

* Only comparing line numbers in test because function names in stack trace seem to be platform dependent.

Author: denniske

packages/expect/src/__tests__/stacktrace.test.js

@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ */
+
+const jestExpect = require('../');
+
+jestExpect.extend({
+  toMatchPredicate(received, argument) {
+    argument(received);
+    return {
+      message: () => '',
+      pass: true,
+    };
+  },
+});
+
+it('stack trace points to correct location when using matchers', () => {
+  try {
+    jestExpect(true).toBe(false);
+  } catch (error) {
+    expect(error.stack).toContain('stacktrace.test.js:24');
+  }
+});
+
+it('stack trace points to correct location when using nested matchers', () => {
+  try {
+    jestExpect(true).toMatchPredicate(value => {
+      jestExpect(value).toBe(false);
+    });
+  } catch (error) {
+    expect(error.stack).toContain('stacktrace.test.js:33');
+  }
+});

packages/expect/src/index.js

@@ -198,10 +198,12 @@ const makeThrowingMatcher = (
     try {
       result = matcher.apply(matcherContext, [actual].concat(args));
     } catch (error) {
-      // Try to remove this and deeper functions from the stack trace frame.
-      // Guard for some environments (browsers) that do not support this feature.
-      if (Error.captureStackTrace) {
-        Error.captureStackTrace(error, throwingMatcher);
+      if (!(error instanceof JestAssertionError)) {
+        // Try to remove this and deeper functions from the stack trace frame.
+        // Guard for some environments (browsers) that do not support this feature.
+        if (Error.captureStackTrace) {
+          Error.captureStackTrace(error, throwingMatcher);
+        }
       }
       throw error;
     }