refactor(ngMock window.inject test): create room for planned tests

Split up `ngMock` `window.inject` tests into tests on browsers supporting
fetching current stack trace information and those not supporting it, as
we plan on adding new test specs to the first group.

Required making the test inject caller function more flexible so it can be
easily configured in different tests without unnecessary code duplication.

Author: jurko-gospodnetic

test/ngMock/angular-mocksSpec.js

@@ -915,52 +915,69 @@ describe('ngMock', function() {
         }).toThrow('test message');
       }));
 
-      describe('when called outside of test spec context and inject callback throws an Error', function() {
-        // - IE9 does not support providing stack traces
-        // - Chrome & Firefox give us the stack trace as soon as an Error is
-        //   created
-        // - IE10, IE11 & PhantomJS give us the stack trace only once the error
-        //   is thrown
-        var stackTraceSupported = (function() {
-          var error = new Error();
-          if (error.stack)
-            return error.stack;
-          try {
-            throw error;
-          } catch (e) {
-            return e.stack;
-          }
-        })();
+      // - IE9 does not support providing stack traces
+      // - Chrome & Firefox give us the stack trace as soon as an Error is
+      //   created
+      // - IE10, IE11 & PhantomJS give us the stack trace only once the error is
+      //   thrown
+      var stackTraceSupported = (function() {
+        var error = new Error();
+        if (error.stack)
+          return error.stack;
+        try {
+          throw error;
+        } catch (e) {
+          return e.stack;
+        }
+      })();
 
-        function testCaller() {
+      function testInjectCaller() {
+        var shouldThrow;
+        var injectingCall = (function internalInjectCaller() {
           return inject(function() {
-            throw new Error();
-          });
-        }
-        var throwErrorFromInjectCallback = testCaller();
-
-        if (stackTraceSupported) {
-          describe('on browsers supporting stack traces', function() {
-              it('should update thrown Error stack with inject call location', function() {
-                try {
-                  throwErrorFromInjectCallback();
-                } catch (e) {
-                  expect(e.stack).toMatch('testCaller');
-                }
-              });
+            if (shouldThrow)
+              throw new Error();
           });
-        } else {
-          describe('on browsers not supporting stack traces', function() {
-            it('should not add stack trace information to thrown Error', function() {
+        })();
+        injectingCall.setThrow = function(value) {
+          shouldThrow = value;
+        };
+        return injectingCall;
+      }
+
+      if (!stackTraceSupported) {
+        describe('on browsers not supporting stack traces', function() {
+          describe('when called outside of test spec context', function() {
+            var injectingCall = testInjectCaller();
+
+            it('should not add stack trace information to thrown injection Error', function() {
+              injectingCall.setThrow(true);
               try {
-                throwErrorFromInjectCallback();
+                injectingCall();
               } catch (e) {
                 expect(e.stack).not.toBeDefined();
               }
             });
           });
-        }
-      });
+        });
+      }
+
+      if (stackTraceSupported) {
+        describe('on browsers supporting stack traces', function() {
+          describe('when called outside of test spec context and injecting throws an Error', function() {
+            var throwingInjectingCall = testInjectCaller();
+            throwingInjectingCall.setThrow(true);
+
+            it('should update thrown Error stack with inject call location', function() {
+              try {
+                throwingInjectingCall();
+              } catch (e) {
+                expect(e.stack).toMatch('testInjectCaller');
+              }
+            });
+          });
+        });
+      }
     });
   });