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Original file line number Diff line number Diff line change
Expand Up @@ -10,3 +10,30 @@ test("Classifies right angles", () => {
const right = getAngleType(90);
assert.equal(right, "Right angle");
});

test("Classifies acute angles", () => {
const acute = getAngleType(45);
assert.equal(acute, "Acute angle");
});

test("classifies obtuse angles", () => {
const obtuse = getAngleType(120);
assert.equal(obtuse, "Obtuse angle");
});

test("classifies straight angles", () => {
const straight = getAngleType(180);
assert.equal(straight, "Straight angle");
});
test("classifies reflex angles", () => {
const reflex = getAngleType(270);
assert.equal(reflex, "Reflex angle");
});
test("classifies invalid negative angles", () => {
const invalid = getAngleType(-10);
assert.equal(invalid, "Invalid angle");
});
test("classifies angles greater than 360 as invalid", () => {
Comment on lines +32 to +36

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Note:

  • Negative angles means angle < 0 but 0 is also invalid. So you could consider specifying when angle <= 0 instead.

  • The description "greater than 360" does not include 360. >= 360 is "greater than or equal to 360".

const invalid = getAngleType(400);
assert.equal(invalid, "Invalid angle");
});
Original file line number Diff line number Diff line change
Expand Up @@ -9,8 +9,34 @@ test("Valid single-digit card", () => {
assert.equal(getCardValue("9♠"), 9);
});

test("Arbitrary non-card string", () => {
assert.throws(() => getCardValue("invalid"), /Expected a number followed by a suit, but got "invalid"/, "Expected clear error");
test("Ace is worth 11", () => {
assert.equal(getCardValue("A♠"), 11);
});
test("Jack is worth 10", () => {
assert.equal(getCardValue("J♠"), 10);
});

test("Queen is worth 10", () => {
assert.equal(getCardValue("Q♠"), 10);
});

test("King is worth 10", () => {
assert.equal(getCardValue("K♠"), 10);
});

test("Ten is worth 10", () => {
assert.equal(getCardValue("10♠"), 10);
});

test("Missing suit is invalid", () => {
assert.throws(() => getCardValue("A"));
});

// TODO: What other invalid card cases can you think of?
test("Arbitrary non-card string", () => {
assert.throws(
() => getCardValue("invalid"),
/Expected a number followed by a suit, but got "invalid"/,
"Expected clear error"
);
});
21 changes: 20 additions & 1 deletion implement-and-rewrite-tests/implement/1-get-angle-type.js
Original file line number Diff line number Diff line change
Expand Up @@ -17,5 +17,24 @@
// execute the code to ensure all tests pass.

export function getAngleType(angle) {
// TODO: Implement this function
if (angle === 90) {
return "Right angle";
}
if (angle > 0 && angle < 90) {
return "Acute angle";
}

if (angle > 90 && angle < 180) {
return "Obtuse angle";
}

if (angle === 180) {
return "Straight angle";
}

if (angle > 180 && angle < 360) {
return "Reflex angle";
}

return "Invalid angle";
}
Original file line number Diff line number Diff line change
Expand Up @@ -14,5 +14,5 @@
// execute the code to ensure all tests pass.

export function isProperFraction(numerator, denominator) {
// TODO: Implement this function
return numerator < denominator;
}
23 changes: 22 additions & 1 deletion implement-and-rewrite-tests/implement/3-get-card-value.js
Original file line number Diff line number Diff line change
Expand Up @@ -24,5 +24,26 @@
// execute the code to ensure all tests pass.

export function getCardValue(card) {
// TODO: Implement this function
const suit = card.slice(-1);
const rank = card.slice(0, -1);

if (!["♠", "♥", "♦", "♣"].includes(suit)) {
throw new Error(`Expected a number followed by a suit, but got "${card}"`);
}

if (rank === "A") {
return 11;
}

if (rank === "J" || rank === "Q" || rank === "K") {
return 10;
}

const value = Number(rank);

if (!isNaN(value) && value >= 2 && value <= 10) {
return value;
}
Comment on lines +41 to +46

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In JavaScript, strings that represent valid numeric literals in the language can be safely converted to equivalent numbers. For examples, "0x02", "2.1", or "0002".

Does your function return the value you expected from each of the following function calls?

getCardValue("0x02♠");
getCardValue("2.1♠");
getCardValue("0002♠");


throw new Error(`Expected a number followed by a suit, but got "${card}"`);
}
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,30 @@ test(`should return "Acute angle" when (0 < angle < 90)`, () => {
});

// Case 2: Right angle
test('should return "right angle" when angle is 90', () => {
expect(getAngleType(90)).toEqual("Right angle");
});
// Case 3: Obtuse angles
test('should return "Obtuse angle" when (90 < angle < 180)', () => {
expect(getAngleType(91)).toEqual("Obtuse angle");
expect(getAngleType(120)).toEqual("Obtuse angle");
expect(getAngleType(179)).toEqual("Obtuse angle");
});
// Case 4: Straight angle
test('should return "Straight angle" when angle is 180', () => {
expect(getAngleType(180)).toEqual("Straight angle");
});
// Case 5: Reflex angles
test('should return "Reflex angle" when (180 < angle < 360)', () => {
expect(getAngleType(181)).toEqual("Reflex angle");
expect(getAngleType(270)).toEqual("Reflex angle");
expect(getAngleType(359)).toEqual("Reflex angle");
});
// Case 6: Invalid angles

test('should return "Invalid angle" for invalid angles', () => {

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An exact range of invalid angles could probably make the test description more informative.

expect(getAngleType(-1)).toEqual("Invalid angle");
expect(getAngleType(0)).toEqual("Invalid angle");
expect(getAngleType(360)).toEqual("Invalid angle");
expect(getAngleType(400)).toEqual("Invalid angle");
});
Original file line number Diff line number Diff line change
Expand Up @@ -6,3 +6,30 @@ import { isProperFraction } from "../implement/2-is-proper-fraction.js";
test(`should return false when denominator is zero`, () => {
expect(isProperFraction(1, 0)).toEqual(false);
});
test("should return true for a proper fraction", () => {
expect(isProperFraction(1, 2)).toEqual(true);
});

test("should return false when numerator equals denominator", () => {
expect(isProperFraction(5, 5)).toEqual(false);
});

test("should return false when numerator is greater than denominator", () => {
expect(isProperFraction(7, 3)).toEqual(false);
});

test("should return true when numerator is zero", () => {
expect(isProperFraction(0, 5)).toEqual(true);
});

test("should return false for negative numerator and denominator", () => {
expect(isProperFraction(-1, -2)).toEqual(false);
});
Comment on lines +25 to +27

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May I ask which authoritative source you used for the definition of a proper fraction?

In math

  • $\frac{-1}{2}$ and $\frac{1}{-2}$ equals $-\frac{1}{2}$
  • $\frac{-1}{-2}$ equals $\frac{1}{2}$


test("should return true for negative numerator and positive denominator", () => {
expect(isProperFraction(-1, 2)).toEqual(true);
});

test("should return false for positive numerator and negative denominator", () => {
expect(isProperFraction(1, -2)).toEqual(false);
});
Original file line number Diff line number Diff line change
Expand Up @@ -9,10 +9,34 @@ test(`Should return 11 when given an ace card`, () => {

// Suggestion: Group the remaining test data into these categories:
// Number Cards (2-10)
test("Should return 2 when given a 2 card", () => {
expect(getCardValue("2♠")).toEqual(2);
});

test("Should return 10 when given a 10 card", () => {
expect(getCardValue("10♠")).toEqual(10);
});

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When preparing tests, we should ensure the tests cover all possible cases. If we specify a test for individual rank, we will need about 13 tests to cover all possible cases. Instead, we could consider classifying all possible values into different categories, and then within each category we test some samples.

For example, one possible category for getCardValue() is, "should return the value of number cards (2-10)", and we can prepare the test as

test("should return the value of number cards (2-10)", () => {
    expect(getCardValue("2♣︎")).toEqual(2);
    expect(getCardValue("5♠")).toEqual(5);
    expect(getCardValue("10♥")).toEqual(10);
    // Note: We could also use a loop to check all values from 2 to 10.
});

Can you practice preparing tests in this fashion?

// Face Cards (J, Q, K)
test("Should return 10 when given a Jack", () => {
expect(getCardValue("J♠")).toEqual(10);
});

test("Should return 10 when given a Queen", () => {
expect(getCardValue("Q♠")).toEqual(10);
});

test("Should return 10 when given a King", () => {
expect(getCardValue("K♠")).toEqual(10);
});
// Invalid Cards
test("Should throw an error for invalid text", () => {
expect(() => getCardValue("invalid")).toThrow();
});

test("Should throw an error when suit is missing", () => {
expect(() => getCardValue("A")).toThrow();
});
Comment on lines +32 to +38

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When testing invalid inputs, focus on edge cases that the function might overlook. Inputs that closely resemble valid card values are especially useful. For example, "A" is a good test case because it contains a valid rank but is missing the suit character.

Can you think of other test cases that resemble valid card values but are still invalid?

An empty string ("") is also always worth testing for any parameter that accepts a string.


// To learn how to test whether a function throws an error as expected in Jest,
// please refer to the Jest documentation:
// https://jestjs.io/docs/expect#tothrowerror

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