package numerics

import "testing"

func TestBisect(t *testing.T) {
	// f(i) = 10*i, monotone increasing.
	f := func(i int) float64 { return 10 * float64(i) }

	// target = 25 → largest i with 10i < 25 is i=2
	if got := Bisect(0, 10, 25, f); got != 2 {
		t.Errorf("Bisect target=25 = %d, want 2", got)
	}

	// target on boundary: target = 30, condition is target <= f(mid) so f(3)=30 → not less; want 2
	if got := Bisect(0, 10, 30, f); got != 2 {
		t.Errorf("Bisect target=30 = %d, want 2", got)
	}

	// target below all values
	if got := Bisect(0, 10, -5, f); got != 0 {
		t.Errorf("Bisect target=-5 = %d, want 0", got)
	}

	// target above all values
	if got := Bisect(0, 10, 1000, f); got != 10 {
		t.Errorf("Bisect target=1000 = %d, want 10", got)
	}
}