diff --git a/projects/from-javascript-to-typescript/the-typeinator/01-syntactic-sugar/index.test.js b/projects/from-javascript-to-typescript/the-typeinator/01-syntactic-sugar/index.test.js
new file mode 100644
index 00000000..544307ac
--- /dev/null
+++ b/projects/from-javascript-to-typescript/the-typeinator/01-syntactic-sugar/index.test.js
@@ -0,0 +1,53 @@
+const { announceMachines } = process.env.TEST_SOLUTIONS
+	? require("./solution")
+	: require("./index");
+
+describe(announceMachines, () => {
+	it("announces a machine's label when the label exists", () => {
+		const announce = jest.fn();
+		const label = "test label";
+
+		announceMachines(announce, { label });
+
+		expect(announce).toHaveBeenCalledWith(label);
+	});
+
+	it("announces a machine's make and model when it does not have a label", () => {
+		const announce = jest.fn();
+		const make = "test make";
+		const model = "test model";
+
+		announceMachines(announce, { make, model });
+
+		expect(announce).toHaveBeenCalledWith(`Make: test make; Model: test model`);
+	});
+
+	it("returns an increased count when a machine has a label", () => {
+		const announce = jest.fn();
+
+		const labelsCount = announceMachines(announce, { label: "test label" });
+
+		expect(labelsCount).toBe(1);
+	});
+
+	it("returns a non-increased count when a machine does not has a label", () => {
+		const announce = jest.fn();
+
+		const labelsCount = announceMachines(announce, { make: "", model: "" });
+
+		expect(labelsCount).toBe(0);
+	});
+
+	it("returns an increased count for labels when only some machines have label", () => {
+		const announce = jest.fn();
+
+		const labelsCount = announceMachines(
+			announce,
+			{ label: "test label" },
+			{ make: "", model: "" },
+			{ label: "test label" },
+		);
+
+		expect(labelsCount).toBe(2);
+	});
+});
diff --git a/projects/from-javascript-to-typescript/the-typeinator/02-prototypes-to-classes/index.test.js b/projects/from-javascript-to-typescript/the-typeinator/02-prototypes-to-classes/index.test.js
new file mode 100644
index 00000000..8b7e9092
--- /dev/null
+++ b/projects/from-javascript-to-typescript/the-typeinator/02-prototypes-to-classes/index.test.js
@@ -0,0 +1,102 @@
+const { Robot, Humanoid } = process.env.TEST_SOLUTIONS
+	? require("./solution")
+	: require("./index");
+
+const log = (console.log = jest.fn());
+
+beforeEach(() => {
+	log.mockClear();
+});
+
+describe(Robot, () => {
+	describe("announce", () => {
+		it("announces name and abilities", () => {
+			const robot = new Robot("The Typeinator", ["refactor", "transpile"]);
+
+			robot.announce();
+
+			expect(log).toHaveBeenCalledWith("Greetings. I am The Typeinator.");
+			expect(log).toHaveBeenCalledWith("I am able to refactor.");
+			expect(log).toHaveBeenCalledWith("I am able to transpile.");
+		});
+	});
+
+	describe("charge", () => {
+		it("does not recharge if power is already at 100", () => {
+			const robot = new Robot("", []);
+
+			robot.charge(1);
+
+			expect(robot.power).toBe(100);
+			expect(log).toHaveBeenCalledWith("I am at optimal operational capacity.");
+			expect(log).not.toHaveBeenCalledWith("Recharged power supplies to 100.");
+		});
+
+		it("recharges by the amount if it would not increase to 100", () => {
+			const robot = new Robot("", []);
+			robot.move(50);
+
+			robot.charge(25);
+			expect(log).toHaveBeenCalledWith("Recharged power supplies to 75.");
+		});
+
+		it("recharges to 100 amount if it would increase beyond 100", () => {
+			const robot = new Robot("", []);
+			robot.move(25);
+
+			robot.charge(50);
+			expect(log).toHaveBeenCalledWith("Recharged power supplies to 100.");
+		});
+	});
+
+	describe("move", () => {
+		it("does not move if there is not enough power", () => {
+			const robot = new Robot("", []);
+
+			robot.move(101);
+
+			expect(log).toHaveBeenCalledWith(
+				"I do not have enough power to move 101 units.",
+			);
+		});
+
+		it("moves and decreases power if there is enough power", () => {
+			const robot = new Robot("", []);
+
+			robot.move(99);
+
+			expect(log).toHaveBeenCalledWith("Moving 99 units.");
+		});
+
+		it("does not move a second time after decreasing power from a first.", () => {
+			const robot = new Robot("", []);
+
+			robot.move(50);
+			robot.move(51);
+
+			expect(log).toHaveBeenCalledWith("Moving 50 units.");
+			expect(log).toHaveBeenCalledWith(
+				"I do not have enough power to move 51 units.",
+			);
+		});
+	});
+});
+
+describe(Humanoid, () => {
+	describe("announce", () => {
+		it("announces name, abilities, and catchphrase", () => {
+			const humanoid = new Humanoid(
+				"The Typeinator",
+				["refactor", "transpile"],
+				"Come with me if you want types.",
+			);
+
+			humanoid.announce();
+
+			expect(log).toHaveBeenCalledWith("Greetings. I am The Typeinator.");
+			expect(log).toHaveBeenCalledWith("I am able to refactor.");
+			expect(log).toHaveBeenCalledWith("I am able to transpile.");
+			expect(log).toHaveBeenCalledWith(" > Come with me if you want types. <");
+		});
+	});
+});
diff --git a/projects/from-javascript-to-typescript/the-typeinator/03-callbacks-to-async-await/index.test.js b/projects/from-javascript-to-typescript/the-typeinator/03-callbacks-to-async-await/index.test.js
new file mode 100644
index 00000000..89367cc5
--- /dev/null
+++ b/projects/from-javascript-to-typescript/the-typeinator/03-callbacks-to-async-await/index.test.js
@@ -0,0 +1,75 @@
+const { checkEmotion, speak } = process.env.TEST_SOLUTIONS
+	? require("./solution")
+	: require("./index");
+
+const simulateSetTimeoutResolve = async (time) => {
+	jest.advanceTimersByTime(time);
+
+	// Wait for a seemingly larger than needed number of resolves,
+	// just in case the code does more async/await than it needs...
+	await Promise.resolve();
+	await Promise.resolve();
+	await Promise.resolve();
+};
+
+describe(checkEmotion, () => {
+	it("does not process the emotion before a second", async () => {
+		const knownEmotions = new Set();
+		let result;
+		checkEmotion(knownEmotions, "joy").then(
+			(hasEmotion) => (result = hasEmotion),
+		);
+
+		await simulateSetTimeoutResolve(999);
+
+		expect(result).toBe(undefined);
+	});
+
+	it("processes a missing emotion as false after a second", async () => {
+		const knownEmotions = new Set();
+		let result;
+		checkEmotion(knownEmotions, "joy").then(
+			(hasEmotion) => (result = hasEmotion),
+		);
+
+		await simulateSetTimeoutResolve(1000);
+
+		expect(result).toBe(false);
+	});
+
+	it("processes a known emotion as true after a second", async () => {
+		const knownEmotions = new Set(["joy"]);
+		let result;
+		checkEmotion(knownEmotions, "joy").then(
+			(hasEmotion) => (result = hasEmotion),
+		);
+
+		await simulateSetTimeoutResolve(1000);
+
+		expect(result).toBe(true);
+	});
+});
+
+describe(speak, () => {
+	it("rejects if the emotion is not known", async () => {
+		const knownEmotions = new Set([]);
+
+		const result = speak(knownEmotions, "joy", "");
+
+		await simulateSetTimeoutResolve(1000);
+
+		return expect(result).rejects.toThrow(
+			new Error(`Does not compute. I do not understand joy.`),
+		);
+	});
+
+	it("returns the phrase and emotion if the emotion is known", async () => {
+		const knownEmotions = new Set(["joy"]);
+
+		const result = speak(knownEmotions, "joy", "Hello, world!");
+
+		await simulateSetTimeoutResolve(1000);
+
+		return expect(result).resolves.toEqual(`"Hello, world!" (joy)`);
+	});
+});