Robot name

typescript/robot-name/robot-name.test.ts

@@ -0,0 +1,142 @@
+import { Robot } from "./robot-name";
+
+const areSequential = (name1: string, name2: string): boolean => {
+  const alpha1 = name1.substr(0, 2);
+  const alpha2 = name2.substr(0, 2);
+  const num1 = Number(name1.substr(2, 3));
+  const num2 = Number(name2.substr(2, 3));
+
+  const numDiff = num2 - num1;
+  const alphaDiff =
+    (alpha2.charCodeAt(0) - alpha1.charCodeAt(0)) * 26 +
+    (alpha2.charCodeAt(1) - alpha1.charCodeAt(1));
+
+  const totalDiff = alphaDiff * 1000 + numDiff;
+
+  return Math.abs(totalDiff) <= 1;
+};
+
+const NAME_RE = /^[A-Z]{2}\d{3}$/;
+const TOTAL_NUMBER_OF_NAMES =
+  26 * // A-Z
+  26 * // A-Z
+  10 * // 0-9
+  10 * // 0-9
+  10; // 0-9
+
+describe("Robot", () => {
+  let robot: Robot;
+
+  beforeEach(() => {
+    robot = new Robot();
+  });
+
+  afterEach(() => {
+    Robot.releaseNames();
+  });
+
+  it("has a name", () => {
+    expect(robot.name).toMatch(NAME_RE);
+  });
+
+  it("name is the same each time", () => {
+    expect(robot.name).toEqual(robot.name);
+  });
+
+  it("different robots have different names", () => {
+    const differentRobot = new Robot();
+    expect(differentRobot.name).not.toEqual(robot.name);
+  });
+
+  it("is able to reset the name", () => {
+    const originalName = robot.name;
+
+    robot.resetName();
+    const newName = robot.name;
+
+    expect(newName).toMatch(NAME_RE);
+    expect(originalName).not.toEqual(newName);
+  });
+
+  it("should set a unique name after reset", () => {
+    const NUMBER_OF_ROBOTS = 10000;
+    const usedNames = new Set();
+
+    usedNames.add(robot.name);
+    for (let i = 0; i < NUMBER_OF_ROBOTS; i++) {
+      robot.resetName();
+      usedNames.add(robot.name);
+    }
+
+    expect(usedNames.size).toEqual(NUMBER_OF_ROBOTS + 1);
+  });
+
+  it("new names should not be sequential", () => {
+    const name1 = robot.name;
+    const name2 = new Robot().name;
+    const name3 = new Robot().name;
+    expect(areSequential(name1, name1)).toBe(true);
+    expect(areSequential(name1, name2)).toBe(false);
+    expect(areSequential(name2, name3)).toBe(false);
+  });
+
+  it("names from reset should not be sequential", () => {
+    const name1 = robot.name;
+    robot.resetName();
+    const name2 = robot.name;
+    robot.resetName();
+    const name3 = robot.name;
+    expect(areSequential(name1, name2)).toBe(false);
+    expect(areSequential(name2, name3)).toBe(false);
+    expect(areSequential(name3, name3)).toBe(true);
+  });
+
+  it("uses all letters", () => {
+    let letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+    for (let i = 0; i < 1000 - 1; i += 1) {
+      const newRobot = new Robot();
+      const lettersInName = newRobot.name.slice(0, 2);
+      letters = letters.replace(lettersInName[0], "");
+      letters = letters.replace(lettersInName[1], "");
+
+      if (letters.length === 0) {
+        break;
+      }
+    }
+    expect(letters).toEqual("");
+  });
+
+  it("uses all numbers", () => {
+    let numbers = "0123456789";
+
+    for (let i = 0; i < 1000 - 1; i += 1) {
+      const newRobot = new Robot();
+      const digitsInName = newRobot.name.slice(2, 5);
+      numbers = numbers.replace(digitsInName[0], "");
+      numbers = numbers.replace(digitsInName[1], "");
+      numbers = numbers.replace(digitsInName[2], "");
+
+      if (numbers.length === 0) {
+        break;
+      }
+    }
+    expect(numbers).toEqual("");
+  });
+
+  // This test is optional.
+  //
+  // This test doesn't run on our online test runner because it will time-out
+  // with most implementations. It's up to you to test your solution locally.
+  it.skip("all the names can be generated", () => {
+    const usedNames = new Set();
+    usedNames.add(robot.name);
+
+    for (let i = 0; i < TOTAL_NUMBER_OF_NAMES - 1; i += 1) {
+      const newRobot = new Robot();
+      usedNames.add(newRobot.name);
+    }
+
+    expect(usedNames.size).toEqual(TOTAL_NUMBER_OF_NAMES);
+  });
+});