Merge pull request #309 from migalko94/feature/#126-Add-Unit-test-sup…

…port-to-history-manager.business.ts

add tests to  can undo can redo perform undo perform redo

src/common/undo-redo/history-manager.business.spec.ts

@@ -0,0 +1,121 @@
+import {
+  canUndo,
+  canRedo,
+  performUndo,
+  performRedo,
+} from './history-manager.business';
+
+describe('common/undo-redo/history-manager.business', () => {
+  describe('canUndo', () => {
+    it('should return true when current index is higher than zero', () => {
+      // Arrange
+      const currentIndex: number = 1;
+      const expectedResult: boolean = true;
+      // Act
+      const result = canUndo(currentIndex);
+      // Assert
+      expect(result).toEqual(expectedResult);
+    });
+
+    it('should return false when current index equals zero', () => {
+      // Arrange
+      const currentIndex: number = 0;
+      const expectedResult: boolean = false;
+      // Act
+      const result = canUndo(currentIndex);
+      // Assert
+      expect(result).toEqual(expectedResult);
+    });
+
+    it('should return false when current index is lower than zero', () => {
+      // Arrange
+      const currentIndex: number = -1;
+      const expectedResult: boolean = false;
+      // Act
+      const result = canUndo(currentIndex);
+      // Assert
+      expect(result).toEqual(expectedResult);
+    });
+  });
+
+  describe('canRedo', () => {
+    it('should return true when current index is lower than history length minus 1', () => {
+      // Arrange
+      const currentIndex: number = 1;
+      const historyLength: number = 3;
+      const expectedResult: boolean = true;
+      // Act
+      const result = canRedo(currentIndex, historyLength);
+      // Assert
+      expect(result).toEqual(expectedResult);
+    });
+
+    it('should return false when current index equals history length minus 1', () => {
+      // Arrange
+      const currentIndex: number = 1;
+      const historyLength: number = 2;
+      const expectedResult: boolean = false;
+      // Act
+      const result = canRedo(currentIndex, historyLength);
+      // Assert
+      expect(result).toEqual(expectedResult);
+    });
+
+    it('should return false when current index is higher than history length minus 1', () => {
+      // Arrange
+      const currentIndex: number = 2;
+      const historyLength: number = 2;
+      const expectedResult: boolean = false;
+      // Act
+      const result = canRedo(currentIndex, historyLength);
+      // Assert
+      expect(result).toEqual(expectedResult);
+    });
+  });
+
+  describe('performUndo', () => {
+    it('should return current index minus 1 when canUndo function with current index as parameter returns true', () => {
+      // Arrange
+      const currentIndex: number = 1;
+      const expectedResult: number = 0;
+      // Act
+      const result = performUndo(currentIndex);
+      // Assert
+      expect(result).toEqual(expectedResult);
+    });
+
+    it('should return current index when canUndo function with current index as parameter returns false', () => {
+      // Arrange
+      const currentIndex: number = 0;
+      const expectedResult: number = 0;
+      // Act
+      const result = performUndo(currentIndex);
+      // Assert
+      expect(result).toEqual(expectedResult);
+    });
+  });
+
+  describe('performRedo', () => {
+    it('should return current index plus 1 when canRedo function with current index and history length as parameters returns true', () => {
+      // Arrange
+      const currentIndex = 1;
+      const historyLength: number = 3;
+      const expectedResult: number = 2;
+      // Act
+      const result = performRedo(currentIndex, historyLength);
+      // Assert
+      expect(result).toEqual(expectedResult);
+    });
+
+    it('should return current index when canRedo function with current index and history length as parameters returns false', () => {
+      // Arrange
+      const currentIndex = 1;
+      const historyLength: number = 2;
+      const expectedResult: number = 1;
+      // Act
+      const result = performRedo(currentIndex, historyLength);
+      // Assert
+      expect(result).toEqual(expectedResult);
+    });
+  });
+});