Fix error message in NewTrack test case

Programming Go
1

noticed that the error message did not make sense when doing a local go test :

my output value and the expected value output as the same, and it took awhile for me to realise i hardcoded a value in the NewTrack struct that was causing the error.
the correct test case should compare against the instantiated struc got

2

The image you attached isn’t rendering so it’s not clear what the error is. Please share it as text.

3

you can refer to the screenshot in this PR Fix error message in NewTrack test case by kahghi · Pull Request #2893 · exercism/go · GitHub

4

Please use text (or a codeblock) to share text, not images :slightly_smiling_face:

Could you share your code and the output as text?

5

i’ve updated the PR with both the error message and my code and the code difference spotted in the test case. hope that it’s clearer :slight_smile:

6

We prefer that discussion happen here, ideally before a PR is opened. To that end, I’ve pasted your PR comments below for visibility.

more details below

error message:

--- FAIL: TestNewTrack (0.00s)
    --- FAIL: TestNewTrack/Create_a_new_track.#01 (0.00s)
        need_for_speed_test.go:68: NewTrack(360) = {distance:360}; expected {distance:360}
FAIL
exit status 1
FAIL	speed	0.405s

need_for_speed.go

package speed

// TODO: define the 'Car' type struct
type Car struct {
	battery int
	batteryDrain int
	speed int
	distance int
}

// NewCar creates a new remote controlled car with full battery and given specifications.
func NewCar(speed, batteryDrain int) Car {
	return Car{
		battery: 100,
		batteryDrain: batteryDrain,
		speed: speed,
		distance: 0,
	}
}

// TODO: define the 'Track' type struct
type Track struct {
	distance int
}

// NewTrack creates a new track
func NewTrack(distance int) Track {
	return Track{
		distance: 800,
	}
}

// Drive drives the car one time. If there is not enough battery to drive one more time,
// the car will not move.
func Drive(car Car) Car {
	if car.battery >= car.batteryDrain {
		car.battery -= car.batteryDrain
		car.distance += car.speed
	}
	return car
}

// CanFinish checks if a car is able to finish a certain track.
func CanFinish(car Car, track Track) bool {
	numberOfTurns := track.distance / car.speed
	overallBatteryRequired := car.batteryDrain * numberOfTurns
	if overallBatteryRequired <= car.battery {
		return true
	} else {
		return false
	}
}

expected behaviour → test should fail and return that distance was assigned as 800, which is different than the expected 360. reality → test failed with detail that the assigned distance was 360, same as the expected value → confusion as i could not understand why the tests were failing when the two values were the same.

went to inspect the test cases in need_for_speed_test.go and realised that TestNewTrack was referencing its own track value in the error message. realised that the comparison should be done against got, similar to TestNewCar

func TestNewTrack(t *testing.T) {
	tests := []struct {
		name     string
		track    Track
		expected Track
	}{
		{
			name: "Create a new track.",
			track: Track{
				distance: 800,
			},
			expected: Track{
				distance: 800,
			},
		},
		{
			name: "Create a new track.",
			track: Track{
				distance: 360,
			},
			expected: Track{
				distance: 360,
			},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got := NewTrack(tt.track.distance)

			if got != tt.expected {
				t.Errorf("NewTrack(%+v) = %+v; expected %+v", tt.track.distance, tt.track, tt.expected)
			}
		})
	}
}

func TestNewCar(t *testing.T) {
	tests := []struct {
		name     string
		car      Car
		expected Car
	}{
		{
			name: "Create a new car.",
			car: Car{
				speed:        5,
				batteryDrain: 2,
				battery:      100,
			},
			expected: Car{
				speed:        5,
				batteryDrain: 2,
				battery:      100,
			},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got := NewCar(tt.car.speed, tt.car.batteryDrain)

			if got != tt.expected {
				t.Errorf("NewCar(%+v,%+v) = %+v; expected %+v", tt.car.speed, tt.car.batteryDrain, got, tt.expected)
			}
		})
	}
}
1 Like
7

@BNAndras @IsaacG is this a valid issue for the PR to be re-raised?

8

That would be a question for the Go maintainer, @andrerfcsantos

It would be helpful to clean up the report, though, so it’s easier to read :slight_smile:

1 Like
9

Merged the PR, thanks for this!

1 Like