Don't let changes to expect.output.preferredWidth propagate into exis…

…ting clones

lib/Unexpected.js

@@ -1637,6 +1637,8 @@ Unexpected.prototype.clone = function() {
   });
   // Install the hooks:
   unexpected._expect = this._expect;
+  // Make sure that changes to the parent's preferredWidth doesn't propagate:
+  unexpected.output.preferredWidth = this.output.preferredWidth;
   return makeExpectFunction(unexpected);
 };
 

test/preferredWidth.spec.js

@@ -0,0 +1,81 @@
+/*global unexpected*/
+
+describe('expect.output.preferredWidth', () => {
+  var expect = unexpected.clone();
+  beforeEach(() => {
+    expect = expect.clone();
+    expect.output.preferredWidth = 9999;
+  });
+
+  describe('and a clone', () => {
+    var clonedExpect;
+    beforeEach(() => {
+      clonedExpect = expect.clone();
+    });
+
+    it('should propagate into the clone', () => {
+      expect(clonedExpect.output.preferredWidth, 'to be', 9999);
+    });
+
+    describe('when the value is changed in the clone', () => {
+      beforeEach(() => {
+        clonedExpect.output.preferredWidth = 7777;
+      });
+
+      it('should not affect the original', () => {
+        expect(expect.output.preferredWidth, 'to be', 9999);
+      });
+    });
+
+    describe('when the value is changed in the original after the clone was made', () => {
+      beforeEach(() => {
+        expect.output.preferredWidth = 5555;
+      });
+
+      it('should not affect the clone', () => {
+        expect(clonedExpect.output.preferredWidth, 'to be', 9999);
+      });
+    });
+  });
+
+  describe('and a child', () => {
+    var childExpect;
+    beforeEach(() => {
+      childExpect = expect.child();
+    });
+
+    it('should propagate into the child', () => {
+      expect(childExpect.output.preferredWidth, 'to be', 9999);
+    });
+
+    describe('when the value is changed in the child', () => {
+      beforeEach(() => {
+        childExpect.output.preferredWidth = 7777;
+      });
+
+      it('should not affect the original', () => {
+        expect(expect.output.preferredWidth, 'to be', 9999);
+      });
+
+      describe('and then in the parent', () => {
+        beforeEach(() => {
+          expect.output.preferredWidth = 4444;
+        });
+
+        it('should not affect the child', () => {
+          expect(childExpect.output.preferredWidth, 'to be', 7777);
+        });
+      });
+    });
+
+    describe('when the value is changed in the original after the child was made', () => {
+      beforeEach(() => {
+        expect.output.preferredWidth = 5555;
+      });
+
+      it('should propagate the change to the child', () => {
+        expect(childExpect.output.preferredWidth, 'to be', 5555);
+      });
+    });
+  });
+});