Add tests for viewDidLoad

Author: tomaszpieczykolan

Tests/UICoreTests/ViewControllerTests.swift

@@ -59,4 +59,56 @@ final class ViewControllerTests: XCTestCase {
 
     XCTAssert(sut.next === expectedResult)
   }
+  
+  func testViewDidLoadMethodCalledAfterLazyViewLoad() {
+    let sut = MockViewController()
+
+    let expectation = self.expectation(description: "viewDidLoad should be called")
+
+    sut.viewDidLoadBlock = {
+      expectation.fulfill()
+    }
+
+    _ = sut.view
+
+    wait(for: [expectation], timeout: 0.1)
+  }
+
+  func testViewDidLoadMethodCalledAfterManualViewLoad() {
+    let sut = MockViewController()
+
+    let expectation = self.expectation(description: "viewDidLoad should be called")
+
+    sut.viewDidLoadBlock = {
+      expectation.fulfill()
+    }
+
+    sut.loadViewIfNeeded()
+
+    wait(for: [expectation], timeout: 0.1)
+  }
+
+func testViewDidLoadMethodNotCalledIfViewNotLoaded() {
+    let sut = MockViewController()
+
+    let expectation = self.expectation(description: "viewDidLoad should not be called")
+    expectation.isInverted = true
+
+    sut.viewDidLoadBlock = {
+      expectation.fulfill()
+    }
+
+    wait(for: [expectation], timeout: 0.1)
+  }
+}
+
+final class MockViewController: ViewController {
+  var viewDidLoadBlock: () -> Void = {
+    XCTFail("Not implemented")
+  }
+
+  override func viewDidLoad() {
+    super.viewDidLoad()
+    viewDidLoadBlock()
+  }
 }