Merge pull request #785 from unexpectedjs/feature/childInheritsFromParentExpect

Add the parent expect to the prototype chain of a child expect

Author: papandreou

lib/createTopLevelExpect.js

@@ -1584,30 +1584,32 @@ expectPrototype.clone = function () {
 
 expectPrototype.child = function () {
   this._assertTopLevelExpect();
-  const childExpect = createTopLevelExpect({
-    assertions: {},
-    types: [],
-    typeByName: {},
-    output: this.output.clone(),
-    format: this.outputFormat(),
-    installedPlugins: [],
-  });
-  const parent = (childExpect.parent = this);
+  const childExpect = createTopLevelExpect(
+    {
+      assertions: {},
+      types: [],
+      typeByName: {},
+      output: this.output.clone(),
+      format: this.outputFormat(),
+      installedPlugins: [],
+    },
+    this
+  );
 
   childExpect.exportAssertion = function (testDescription, handler) {
-    parent.addAssertion(testDescription, handler, childExpect);
+    childExpect.parent.addAssertion(testDescription, handler, childExpect);
     return this;
   };
   childExpect.exportType = function (type) {
     if (childExpect.getType(type.name) !== type) {
       childExpect.addType(type);
     }
 
-    parent.addType(type, childExpect);
+    childExpect.parent.addType(type, childExpect);
     return this;
   };
   childExpect.exportStyle = function (name, handler, allowRedefinition) {
-    parent.addStyle(
+    childExpect.parent.addStyle(
       name,
       function (...args) {
         const childOutput = childExpect.createOutput(this.format);
@@ -1907,18 +1909,26 @@ Object.defineProperty(expectPrototype, 'argTypes', {
   },
 });
 
-function createTopLevelExpect({
-  assertions = {},
-  typeByName = { any: anyType },
-  types = [anyType],
-  output,
-  format = magicpen.defaultFormat,
-  installedPlugins = [],
-} = {}) {
+function createTopLevelExpect(
+  {
+    assertions = {},
+    typeByName = { any: anyType },
+    types = [anyType],
+    output,
+    format = magicpen.defaultFormat,
+    installedPlugins = [],
+  } = {},
+  parentExpect
+) {
   const expect = function (...args) {
     return expect._expect(new Context(), args);
   };
-  utils.setPrototypeOfOrExtend(expect, expectPrototype);
+  if (parentExpect) {
+    expect.parent = parentExpect;
+    utils.setPrototypeOfOrExtend(expect, parentExpect);
+  } else {
+    utils.setPrototypeOfOrExtend(expect, expectPrototype);
+  }
 
   if (!output) {
     output = magicpen();
@@ -1928,6 +1938,7 @@ function createTopLevelExpect({
   return extend(expect, {
     _topLevelExpect: expect,
     _outputFormat: format,
+    _frozen: false,
     assertions,
     typeByName,
     installedPlugins,

test/api/hook.js

@@ -46,7 +46,7 @@ describe('hook', () => {
   });
 
   describe('with expect.child', () => {
-    it('should not affect child instances made before installing the hook', () => {
+    it('should affect child instances made before installing the hook', () => {
       const parentExpect = expect.clone();
       const childExpect = parentExpect.child();
 
@@ -59,7 +59,7 @@ describe('hook', () => {
       });
 
       childExpect(123, 'to equal', 123);
-      expect(called, 'to be false');
+      expect(called, 'to be true');
     });
 
     it('should not affect child instances made after installing the hook', () => {
@@ -128,7 +128,8 @@ describe('hook', () => {
 
   // Regression test for https://gitter.im/unexpectedjs/unexpected?at=5fb42b73747be107c1c76095
   it('should not break `this` in clones created after installing the hook', function () {
-    expect.hook(function (next) {
+    const parentExpect = expect.clone();
+    parentExpect.hook(function (next) {
       return function (context, ...rest) {
         return next(context, ...rest);
       };