Go test is failing, even if my function is returning expected result

Getting Help
1 
package sqrt

func Sqrt(num int64) float64 {
	const precision = 0.001

	i := int64(1)
	for ; i*i <= num; i++ {
	}
	result := float64(i - 1)

	for ; result*result <= float64(num); result += precision {

	}
	return result - precision
}

package sqrt

import "testing"

var sqrtTests = []struct {
	num    int64
	result float64
}{
	{9, 3.0},
	{10, 3.162},
	{5, 2.236},
	{97, 9.848},
	{16, 4.0},
}

func TestSqrt(t *testing.T) {
	for _, tt := range sqrtTests {
		if got := Sqrt(tt.num); got != tt.result {
			t.Errorf("got: Sqrt(%d)=%f, want: Sqrt(%d)=%f", tt.num, got, tt.num, tt.result)
		}
	}
}


[okumar@oshank-pc:sqrt]🎩 go test 
--- FAIL: TestSqrt (0.00s)
    sqrt_test.go:19: got: Sqrt(10)=3.162000, want: Sqrt(10)=3.162000
    sqrt_test.go:19: got: Sqrt(5)=2.236000, want: Sqrt(5)=2.236000
    sqrt_test.go:19: got: Sqrt(97)=9.848000, want: Sqrt(97)=9.848000
FAIL
exit status 1
FAIL    <http://github.com/oshankfriends/go-examples/sqrt|github.com/oshankfriends/go-examples/sqrt>       0.001s
2

The difference is probably somewhere behind the stripped part. One doesn’t compare floating point numbers with the equality comparator.

One does check if they are within an allowed delta to the target value.

2 Likes
3

Replace it with a call to a function like this:

func EqualFloat(a, b, precision float64) bool {
	diff := a - b
	if diff < 0.0 {
		diff = -diff
	}
	return diff < precision
}
1 Like
4

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