// Package testutil provides lightweight test helpers to reduce boilerplate in
// table-driven tests. Import it from any _test.go file in this module.
//
// Every helper calls t.Helper() so failures are reported at the call site, not
// inside this package.
package testutil

import (
	"strings"
	"testing"

	"gitea.djmil.dev/go/template/pkg/result"
)

// NoError fails the test immediately if err is not nil.
func NoError(t *testing.T, err error) {
	t.Helper()
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
}

// Error fails the test if err is nil.
func Error(t *testing.T, err error) {
	t.Helper()
	if err == nil {
		t.Fatal("expected error, got nil")
	}
}

// ErrorContains fails the test if err is nil or its message does not contain substr.
func ErrorContains(t *testing.T, err error, substr string) {
	t.Helper()
	Error(t, err)
	if !strings.Contains(err.Error(), substr) {
		t.Errorf("error %q does not contain %q", err.Error(), substr)
	}
}

// Equal fails the test if got != want.
func Equal[T comparable](t *testing.T, got, want T) {
	t.Helper()
	if got != want {
		t.Errorf("got %v, want %v", got, want)
	}
}

// ResultOk fails the test if r holds an error, then returns the value.
func ResultOk[T any](t *testing.T, r result.Expect[T]) T {
	t.Helper()
	if r.Err() != nil {
		t.Fatalf("unexpected error: %v", r.Err())
	}
	return r.Value()
}

// ResultOkNotNil fails the test if r holds an error or its value is nil.
// T must be a pointer type.
func ResultOkNotNil[T comparable](t *testing.T, r result.Expect[T]) T {
	t.Helper()
	v := ResultOk(t, r)
	var zero T
	if v == zero {
		t.Fatal("expected non-nil value, got nil")
	}
	return v
}

// ResultErr fails the test if r does not hold an error.
func ResultErr[T any](t *testing.T, r result.Expect[T]) {
	t.Helper()
	if r.Err() == nil {
		t.Fatal("expected error, got nil")
	}
}