components/FlexibleHeader/tests/unit/FlexibleHeaderTrackingScrollViewTests.swift

/*
Copyright 2016-present the Material Components for iOS authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

import XCTest
import MaterialComponents

// Tests confirming contract with a tracking scroll view that isn't scrolling
class FlexibleHeaderTrackingScrollViewTests: XCTestCase, UIScrollViewDelegate {

  // Implicitly unwrapped to indicate the contract of creating these values in setUp and make our
  // accessors cleaner in tests.
  var view: MDCFlexibleHeaderView!
  var beforeFrame: CGRect!
  var scrollView: UIScrollView!
  var contentOffset = CGPoint(x: 0, y: 0)
  var contentOffsetPtr: UnsafeMutablePointer<CGPoint>?

  override func setUp() {
    view = MDCFlexibleHeaderView()

    let originalFrame = CGRect(x: 0, y: 0, width: 100, height: 50)
    view.frame = originalFrame
    view.sizeToFit()

    beforeFrame = view.frame

    scrollView = UIScrollView()
    scrollView.contentSize = CGSize(width: originalFrame.size.width, height: 1000)
    scrollView.frame = CGRect(x: 0, y: 0, width: originalFrame.size.width, height: 250)

    scrollView.delegate = self

    view.trackingScrollView = scrollView
    contentOffsetPtr = UnsafeMutablePointer<CGPoint>(&contentOffset)
  }

  // MARK: UIScrollViewDelegate events

  func testDidScroll() {
    view.trackingScrollDidScroll()

    XCTAssertEqual(beforeFrame, view.frame)
  }

  func testDidEndDraggingWillDecelerate() {
    view.trackingScrollDidEndDraggingWillDecelerate(true)

    XCTAssertEqual(beforeFrame, view.frame)
  }

  func testDidEndDraggingWillNotDecelerate() {
    view.trackingScrollDidEndDraggingWillDecelerate(false)

    XCTAssertEqual(beforeFrame, view.frame)
  }

  func testDidEndDecelerating() {
    view.trackingScrollDidEndDecelerating()

    XCTAssertEqual(beforeFrame, view.frame)
  }

  func testWillEndDraggingWithZeroVelocity() {
    view.trackingScrollWillEndDragging(
      withVelocity: CGPoint.zero,
      targetContentOffset: contentOffsetPtr!)

    XCTAssertEqual(beforeFrame, view.frame)
  }

  func testWillEndDraggingWithPositiveVelocity() {
    view.trackingScrollWillEndDragging(
      withVelocity: CGPoint(x: 0, y: 10),
      targetContentOffset: contentOffsetPtr!)

    XCTAssertEqual(beforeFrame, view.frame)
  }

  func testWillEndDraggingWithNegativeVelocity() {
    view.trackingScrollWillEndDragging(
      withVelocity: CGPoint(x: 0, y: 10),
      targetContentOffset: contentOffsetPtr!)

    XCTAssertEqual(beforeFrame, view.frame)
  }

  // MARK: Changing the tracking scroll view

  func testWillChangeToNilScrollView() {
    view.trackingScrollWillChange(toScroll: nil)

    XCTAssertEqual(beforeFrame, view.frame)
  }

  // MARK: Shifting header on screen

  func testShiftHeaderOnScreen() {
    view.shiftHeaderOnScreen(animated: false)

    XCTAssertEqual(beforeFrame, view.frame)
  }

  // MARK: Interface orientation changes

  func testInterfaceOrientationWillChange() {
    view.interfaceOrientationWillChange()

    XCTAssertEqual(beforeFrame, view.frame)
  }

  func testInterfaceOrientationIsChanging() {
    view.interfaceOrientationWillChange() // Required by interfaceOrientationIsChanging
    view.interfaceOrientationIsChanging()

    XCTAssertEqual(beforeFrame, view.frame)
  }

  func testInterfaceOrientationDidChange() {
    view.interfaceOrientationWillChange() // Required by interfaceOrientationDidChange
    view.interfaceOrientationDidChange()

    XCTAssertEqual(beforeFrame, view.frame)
  }

  // MARK: Content insets

  func testChangeContentInsets() {
    view.changeContentInsets { } // no-op

    XCTAssertEqual(beforeFrame, view.frame)
  }

  // MARK: UIScrollViewDelegate

  func scrollViewDidScroll(_ scrollView: UIScrollView) {
    if view.trackingScrollView == scrollView {
      view.trackingScrollDidScroll()
    }
  }

  func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
    if view.trackingScrollView == scrollView {
      view.trackingScrollDidEndDraggingWillDecelerate(decelerate)
    }
  }

  func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
    if view.trackingScrollView == scrollView {
      view.trackingScrollDidEndDecelerating()
    }
  }

  func scrollViewWillEndDragging(
      _ scrollView: UIScrollView,
      withVelocity velocity: CGPoint,
      targetContentOffset: UnsafeMutablePointer<CGPoint>) {
    if view.trackingScrollView == scrollView {
      view.trackingScrollWillEndDragging(
        withVelocity: velocity,
        targetContentOffset: targetContentOffset)
    }
  }
}