68 lines
1.5 KiB
Go
68 lines
1.5 KiB
Go
package fixed
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import "testing"
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func TestFromIntAndBack(t *testing.T) {
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if got := FromInt(7).Int(); got != 7 {
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t.Fatalf("FromInt(7).Int() = %d, want 7", got)
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}
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}
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func TestMulIsExact(t *testing.T) {
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half := One / 2
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if got := half.Mul(half); got != One/4 {
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t.Fatalf("0.5*0.5 = %d, want %d", got, One/4)
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}
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}
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func TestMulDoesNotOverflowAtScale(t *testing.T) {
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// A naive (a*b)>>32 overflows well below this. The 128-bit intermediate
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// must handle it exactly.
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a := FromInt(100000)
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if got := a.Mul(FromInt(2)); got != FromInt(200000) {
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t.Fatalf("100000*2 = %v, want 200000", got)
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}
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}
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func TestDivIsExact(t *testing.T) {
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if got := FromInt(1).Div(FromInt(4)); got != One/4 {
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t.Fatalf("1/4 = %d, want %d", got, One/4)
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}
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}
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func TestNegativeMulAndDiv(t *testing.T) {
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if got := FromInt(-3).Mul(FromInt(4)); got != FromInt(-12) {
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t.Fatalf("-3*4 = %v, want -12", got)
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}
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if got := FromInt(-12).Div(FromInt(4)); got != FromInt(-3) {
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t.Fatalf("-12/4 = %v, want -3", got)
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}
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}
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func TestSqrt(t *testing.T) {
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for _, n := range []int64{0, 1, 4, 9, 16, 100, 10000} {
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want := FromInt(isqrt(n))
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got := Sqrt(FromInt(n))
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if got != want {
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t.Fatalf("Sqrt(%d) = %v, want %v", n, got, want)
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}
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}
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}
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func isqrt(n int64) int64 {
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var r int64
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for r*r <= n {
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r++
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}
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return r - 1
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}
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func TestString(t *testing.T) {
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if got := (One + One/2).String(); got != "1.500000" {
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t.Fatalf("1.5.String() = %q", got)
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}
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if got := FromInt(-2).String(); got != "-2.000000" {
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t.Fatalf("-2.String() = %q", got)
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}
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}
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