package cuda

import (
	"testing"
)

func TestBuildDeviceMap(t *testing.T) {
	tests := []struct {
		name    string
		source  []string
		target  []string
		want    string
		wantErr bool
	}{
		{
			name:   "single GPU",
			source: []string{"GPU-aaa"},
			target: []string{"GPU-bbb"},
			want:   "GPU-aaa=GPU-bbb",
		},
		{
			name:   "multiple GPUs",
			source: []string{"GPU-aaa", "GPU-bbb"},
			target: []string{"GPU-ccc", "GPU-ddd"},
			want:   "GPU-aaa=GPU-ccc,GPU-bbb=GPU-ddd",
		},
		{
			name:    "mismatched lengths",
			source:  []string{"GPU-aaa", "GPU-bbb"},
			target:  []string{"GPU-ccc"},
			wantErr: true,
		},
		{
			name:    "both empty",
			source:  []string{},
			target:  []string{},
			wantErr: true,
		},
		{
			name:    "source empty target non-empty",
			source:  []string{},
			target:  []string{"GPU-aaa"},
			wantErr: true,
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			got, err := BuildDeviceMap(tc.source, tc.target)
			if tc.wantErr {
				if err == nil {
					t.Errorf("expected error, got %q", got)
				}
				return
			}
			if err != nil {
				t.Fatalf("unexpected error: %v", err)
			}
			if got != tc.want {
				t.Errorf("got %q, want %q", got, tc.want)
			}
		})
	}
}