title: multiple testPerformance with XCTestCase objective-C
body: <p>I have 2 performance test methods in test class. If i run them separately they pass. If i run hole class methods they fail with message:</p>
  
  <p>**** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'API violation - multiple calls made to -[XCTestExpectation fulfill].'*</p>
  
  <p>Is there any way to include couple performance tests in 1 class?</p>
  
  <p>here is sample code:</p>
  
  <pre><code>- (void)testPerformanceAuthenticateWithLogin {
      XCTestExpectation *authenticateExpectation = [self expectationWithDescription:@"Authenticate With Login"];
      __block int userID = 0;
      [self measureBlock:^{
          [AuthenticationService authenticateWithLogin:email password:password success:^(AuthenticationResponse *result) {
              XCTAssert(result.isAuthenticated);
              userID = result.userID;
              [authenticateExpectation fulfill];
          } failure:^(NSError *error) {
              XCTAssertNil(error);
          }];
      }];
      [self waitForExpectationsWithTimeout:3 handler:^(NSError *error) {
          XCTAssertNil(error);
          [AuthenticationService logoutWithServicePersonID:userID success:nil failure:nil];
      }];
  }
  
  - (void)testPerformanceGetServicePersonByID {
      XCTestExpectation *getServicePersonExpectation = [self expectationWithDescription:@"get Service Person By ID"];
      __block int userID = 0;
      [AuthenticationService authenticateWithLogin:email password:password success:^(AuthenticationResponse *result) {
          userID = result.userID;
          [self loginSuccess:result];
          [self measureBlock:^{
              [ServicePersonService getServicePersonByIDWithServicePersonID:userID success:^(ServicePersonDTO *result) {
                  XCTAssertNotNil(result);
                  [getServicePersonExpectation fulfill];
              } failure:^(NSError *error) {
                  XCTAssertNil(error);
              }];
          }];
      } failure:^(NSError *error) {
          XCTAssertNil(error);
      }];
  
      [self waitForExpectationsWithTimeout:3 handler:^(NSError *error) {
          XCTAssertNil(error);
          [AuthenticationService logoutWithServicePersonID:userID success:nil failure:nil];
      }];
  }
  </code></pre>