From fcb612ca4bac56d8d4950f276241477d1f68a0e7 Mon Sep 17 00:00:00 2001
From: Matt Phillips <matt@mattphillips.io>
Date: Tue, 23 Oct 2018 14:12:44 +0100
Subject: [PATCH] Add error call site to preserve stack trace;

---
 src/chain.js      | 18 ++++++++++++++++--
 src/chain.test.js | 13 +++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/chain.js b/src/chain.js
index 07a899b..879eecb 100644
--- a/src/chain.js
+++ b/src/chain.js
@@ -1,13 +1,27 @@
+class JestAssertionError extends Error {
+  constructor(result, callsite) {
+    super(result.message());
+    this.matcherResult = result;
+
+    if (Error.captureStackTrace) {
+      Error.captureStackTrace(this, callsite);
+    }
+  }
+}
+
 const chainMatchers = (matchers, originalMatchers = matchers) => {
   const mappedMatchers = Object.keys(matchers).map(name => {
     const matcher = matchers[name];
     if (typeof matcher === 'function') {
-      return {
-        [name]: (...args) => {
+      const newMatcher = (...args) => {
+        try {
           matcher(...args); // run matcher
           return chainMatchers(originalMatchers); // chain the original matchers again
+        } catch (error) {
+          throw new JestAssertionError(error.matcherResult, newMatcher);
         }
       };
+      return { [name]: newMatcher };
     }
     return {
       [name]: chainMatchers(matcher, originalMatchers) // recurse on .not/.resolves/.rejects
diff --git a/src/chain.test.js b/src/chain.test.js
index 0f7388b..2f9f81c 100644
--- a/src/chain.test.js
+++ b/src/chain.test.js
@@ -187,4 +187,17 @@ describe('.chain', () => {
     expect(extendMock).toHaveBeenCalledWith(newMatcher);
     expect(actual).toContainAllKeys(['a', 'extend', 'newMatcher']);
   });
+
+  it('throws error when matcher fails', () => {
+    expect.assertions(1);
+    const expectMock = jest.fn(() => ({
+      toBe: () => {
+        const error = new Error('');
+        error.matcherResult = { message: () => 'blah', pass: false };
+        throw error;
+      }
+    }));
+
+    expect(() => chain(expectMock)('hello').toBe('hi')).toThrowErrorMatchingInlineSnapshot('"blah"');
+  });
 });