From facdf20703bb7f4bbfe5b185cbf7c845f27b7ed1 Mon Sep 17 00:00:00 2001
From: Rhys Evans <rhys.evans@ft.com>
Date: Mon, 4 May 2020 21:27:22 +0100
Subject: [PATCH] don't break when using jest.restoreAllMocks()

---
 __tests__/jest-built-ins.spec.js |  1 -
 __tests__/regressions.spec.js    | 20 ++++++++++++++++++++
 jestify.js                       | 26 ++++++++++++++++++--------
 3 files changed, 38 insertions(+), 9 deletions(-)
 create mode 100644 __tests__/regressions.spec.js

diff --git a/__tests__/jest-built-ins.spec.js b/__tests__/jest-built-ins.spec.js
index d6568e4..35c05d9 100644
--- a/__tests__/jest-built-ins.spec.js
+++ b/__tests__/jest-built-ins.spec.js
@@ -78,7 +78,6 @@ describe('jest built-ins', () => {
 		it('mockReset', () => {
 			expect(fetch.mockReset).toBeDefined();
 			fetch.mockReset();
-
 			expect(fetch.mock.calls.length).toEqual(0);
 			expect(fetch._calls.length).toEqual(0);
 			expect(fetch.routes.length).toEqual(0);
diff --git a/__tests__/regressions.spec.js b/__tests__/regressions.spec.js
new file mode 100644
index 0000000..21f7425
--- /dev/null
+++ b/__tests__/regressions.spec.js
@@ -0,0 +1,20 @@
+/*global jest */
+jest.mock('node-fetch', () => require('../server').sandbox());
+const fetch = require('node-fetch');
+
+describe('regressions and strange cases', () => {
+	it('works even when jest.resetAllMocks() is called', () => {
+		jest.resetAllMocks();
+		fetch.mock('*', 200);
+		fetch('http://example.com/path', 200);
+		expect(fetch).toHaveFetched('http://example.com/path');
+		fetch.reset();
+	});
+	it('works even when jest.clearAllMocks() is called', () => {
+		jest.clearAllMocks();
+		fetch.mock('*', 200);
+		fetch('http://example.com/path', 200);
+		expect(fetch).toHaveFetched('http://example.com/path');
+		fetch.reset();
+	});
+});
diff --git a/jestify.js b/jestify.js
index b25d9d8..79107bf 100644
--- a/jestify.js
+++ b/jestify.js
@@ -18,24 +18,34 @@ const jestify = (fetchMockInstance) => {
 
 	// spy on the fetch handler so we can use all the
 	// jest function assertions on it
-	jest.spyOn(jestifiedInstance, 'fetchHandler');
+	const spy = jest.fn();
+	const originalFetchHandler = jestifiedInstance.fetchHandler.bind(
+		jestifiedInstance
+	);
+
+	jestifiedInstance.fetchHandler = function (...args) {
+		const result = originalFetchHandler(...args);
+		spy.mockReturnValueOnce(result);
+		spy.apply(this, args);
+		return result;
+	};
 
 	// make sure all the jest expectation helpers can find what they need on fetchMock.mock
-	Object.assign(jestifiedInstance.mock, jestifiedInstance.fetchHandler.mock);
+	Object.assign(jestifiedInstance.mock, spy.mock);
 
 	['_isMockFunction', 'mockName', 'getMockName'].forEach((prop) => {
-		jestifiedInstance[prop] = jestifiedInstance.fetchHandler[prop];
+		jestifiedInstance[prop] = spy[prop];
 	});
 
 	jestifiedInstance.mockClear = () => {
-		jestifiedInstance.fetchHandler.mockClear();
+		spy.mockClear();
 		jestifiedInstance.resetHistory();
-		Object.assign(jestifiedInstance.mock, jestifiedInstance.fetchHandler.mock);
+		Object.assign(jestifiedInstance.mock, spy.mock);
 	};
 	jestifiedInstance.mockReset = () => {
-		jestifiedInstance.fetchHandler.mockReset();
+		spy.mockReset();
 		jestifiedInstance.reset();
-		Object.assign(jestifiedInstance.mock, jestifiedInstance.fetchHandler.mock);
+		Object.assign(jestifiedInstance.mock, spy.mock);
 	};
 	jestifiedInstance.mockRestore = () => {
 		throw new Error(
@@ -95,7 +105,7 @@ const jestify = (fetchMockInstance) => {
 
 	// make sure that the mock object that has properties updated
 	// by the jest spy is the one that is exposed on fetch
-	jestifiedInstance.fetchHandler.mock = jestifiedInstance.mock;
+	spy.mock = jestifiedInstance.mock;
 
 	// Return this monster!
 	return jestifiedInstance;