Introduce matchers#toBeInstanceOf

src/core/matchers/requireMatchers.js

@@ -4,6 +4,7 @@ getJasmineRequireObj().requireMatchers = function(jRequire, j$) {
       'toBe',
       'toBeCloseTo',
       'toBeDefined',
+      'toBeInstanceOf',
       'toBeFalse',
       'toBeFalsy',
       'toBeGreaterThan',

src/core/matchers/toBeInstanceOf.js

@@ -0,0 +1,45 @@
+getJasmineRequireObj().toBeInstanceOf = function(j$) {
+  var usageError =  j$.formatErrorMsg('<toBeInstanceOf>', 'expect(value).toBeInstanceOf(<ConstructorFunction>)');
+
+  /**
+   * {@link expect} the actual to be an instance of the expected class
+   * @function
+   * @name matchers#toBeInstanceOf
+   * @param {Object} expected - The class or constructor function to check for
+   * @example
+   * expect('foo').toBeInstanceOf(String);
+   * expect(3).toBeInstanceOf(Number);
+   * expect(new Error()).toBeInstanceOf(Error);
+   */
+  function toBeInstanceOf(util, customEqualityTesters) {
+    return {
+      compare: function(actual, expected) {
+        var actualType = actual && actual.constructor ? j$.fnNameFor(actual.constructor) : j$.pp(actual),
+            expectedType = expected ? j$.fnNameFor(expected) : j$.pp(expected),
+            expectedMatcher,
+            pass;
+
+        try {
+            expectedMatcher = new j$.Any(expected);
+            pass = expectedMatcher.asymmetricMatch(actual);
+        } catch (error) {
+            throw new Error(usageError('Expected value is not a constructor function'));
+        }
+
+        if (pass) {
+          return {
+            pass: true,
+            message: 'Expected instance of ' + actualType + ' not to be an instance of ' + expectedType
+          };
+        } else {
+          return {
+            pass: false,
+            message: 'Expected instance of ' + actualType + ' to be an instance of ' + expectedType
+          };
+        }
+      }
+    };
+  }
+
+  return toBeInstanceOf;
+};