0_numberStack - test and implementation

ts-testing-training/src/0_numberStack/index.test.ts

@@ -1,5 +1,48 @@
-describe('Stack', () => {
-  it('should do stuff', () => {
-    // do stuff!
+import {NumberStack} from './index';
+
+describe('NumberStack', () => {
+  let testSubject: NumberStack;
+  beforeEach(() => {
+    testSubject = new NumberStack();
+  });
+
+  it('should not return a value after push call', () => {
+    expect(testSubject.push(10)).toBe(undefined);
+  });
+
+  it('should return the last pushed value on pop() call', () => {
+    testSubject.push(10);
+    testSubject.push(5.5);
+
+    expect(testSubject.pop()).toStrictEqual(5.5);
+  });
+
+  it('should return the correct value after subsequent pop() calls', () => {
+    testSubject.push(10);
+    testSubject.push(5.5);
+
+    testSubject.pop();
+    expect(testSubject.pop()).toStrictEqual(10);
+  });
+
+  it('should return the contents by accessing the contents property', () => {
+    testSubject.push(10);
+    testSubject.push(5.5);
+    const result = testSubject.contents;
+    expect(result.length).toStrictEqual(2);
+  });
+
+  it('should return the last inserted value on top', () => {
+    testSubject.push(10);
+    testSubject.push(5.5);
+
+    expect(testSubject.top).toStrictEqual(5.5);
+  });
+
+  it('should return the same value after subsequent top() calls', () => {
+    testSubject.push(10);
+    testSubject.push(5.5);
+
+    expect(testSubject.top).toStrictEqual(testSubject.top);
   });
 });

ts-testing-training/src/0_numberStack/index.ts

@@ -36,24 +36,24 @@ export class NumberStack {
 
   /** Puts a number on the top of the stack */
   public push(input: number): void {
-    return;
+    this.list.push(input);
   }
 
   /** Remove the most recently pushed number from the stack and return it */
-  public pop(): number {
-    return 0;
+  public pop(): number | undefined {
+    return this.list.pop();
   }
 
   /**
    * Returns the most recently pushed number in the stack.  Does not modify the
    * contents of the stack itself
    */
-  get top(): number {
-    return 0;
+  get top(): number | undefined {
+    return this.list[this.list.length-1];
   }
 
   /** Returns all the contents of the stack */
   get contents(): number[] {
-    return [];
+    return this.list;
   }
 }