mock expects should return an Expectation, rather than a ExpectationStatic.

http://sinonjs.org/docs/#mocks

sinon/sinon-1.5.d.ts

@@ -142,7 +142,7 @@ interface SinonExpectationStatic {
 }
 
 interface SinonMock {
-	expects(method: string): SinonExpectationStatic;
+	expects(method: string): SinonExpectation;
 	restore(): void;
 	verify(): void;
 }

sinon/sinon-tests.ts

@@ -69,9 +69,17 @@ function testSix() {
 	stub.restore();
 }
 
+function testSeven() {
+	var obj = { functionToTest : function () { } };
+	var mockObj = sinon.mock(obj);
+	obj.functionToTest();
+	mockObj.expects('functionToTest').once();
+}
+
 testOne();
 testTwo();
 testThree();
 testFour();
 testFive();
-testSix();
+testSix();
+testSeven();