refactor: allow for invalid dimensions error on NewBoard

board.go

@@ -20,7 +20,11 @@ type position struct{ x, y int }
 // the center point.
 //
 // x 0→n, y 0↓n.
-func NewBoard(x, y int) *Board {
+func NewBoard(x, y int) (*Board, error) {
+	if x <= 0 || y <= 0 {
+		return nil, errors.New("invalid dimensions")
+	}
+
 	data := make([]uint8, x*y)
 
 	b := Board{
@@ -30,10 +34,7 @@ func NewBoard(x, y int) *Board {
 	}
 
 	err := b.setStartPos(x/2, y/2)
-	if err != nil {
-		panic(err) // should be unreachable in current usage
-	}
-	return &b
+	return &b, err
 }
 
 func (b *Board) setStartPos(x, y int) error {

board_test.go

@@ -14,6 +14,33 @@ import (
 	"testing"
 )
 
+func TestNewBoard(t *testing.T) {
+	type args struct {
+		x, y int
+	}
+	tests := []struct {
+		name    string
+		args    args
+		wantErr bool
+	}{
+		{args: args{x: 0, y: 0}, wantErr: true},
+		{args: args{x: 1, y: 0}, wantErr: true},
+		{args: args{x: 0, y: 1}, wantErr: true},
+		{args: args{x: 1, y: 1}, wantErr: false},
+		{args: args{x: -1, y: 1}, wantErr: true},
+		{args: args{x: 10, y: 10}, wantErr: false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			_, err := NewBoard(tt.args.x, tt.args.y)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("NewBoard(%v, %v) error = %v, wantErr %v", tt.args.x, tt.args.y, err, tt.wantErr)
+				return
+			}
+		})
+	}
+}
+
 func TestBoard_Write(t *testing.T) {
 	type state struct {
 		data  []uint8
@@ -50,7 +77,10 @@ func TestBoard_Write(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(base64.RawStdEncoding.EncodeToString(tt.fingerprint), func(t *testing.T) {
-			b := NewBoard(tt.dimX, tt.dimY)
+			b, err := NewBoard(tt.dimX, tt.dimY)
+			if err != nil {
+				t.Fatal(err)
+			}
 			gotN, err := b.Write(tt.fingerprint)
 			// check for error (always false currently, just there for io.Writer
 			if (err != nil) != tt.wantErr {
@@ -108,8 +138,16 @@ func TestBoard_Render(t *testing.T) {
 					filename := strings.Join([]string{slug, specifier, "txt"}, ".")
 					path := filepath.Join("testdata", filename)
 
-					board := NewBoard(rc.dimX, rc.dimY)
-					_, _ = board.Write(dc)
+					board, err := NewBoard(rc.dimX, rc.dimY)
+					if err != nil {
+						t.Fatal(err)
+					}
+
+					_, err = board.Write(dc)
+					if err != nil {
+						t.Fatal(err)
+					}
+
 					got := board.Render(rc.tiles)
 					if rc.armor {
 						got = Armor(got)
@@ -165,12 +203,12 @@ func BenchmarkNewBoard(b *testing.B) {
 	b.ReportAllocs()
 	b.Run("10x10", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			_ = NewBoard(10, 10)
+			_, _ = NewBoard(10, 10)
 		}
 	})
 	b.Run("17x9", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			_ = NewBoard(17, 9)
+			_, _ = NewBoard(17, 9)
 		}
 	})
 }
@@ -180,15 +218,23 @@ func BenchmarkBoard_Write(b *testing.B) {
 	b.SetBytes(int64(len(data)))
 	b.ReportAllocs()
 
-	board := NewBoard(17, 9)
+	board, err := NewBoard(17, 9)
+	if err != nil {
+		b.Fatal(err)
+	}
+
 	for i := 0; i < b.N; i++ {
 		board.Write(data)
 	}
 }
 
 func BenchmarkBoard_Render(b *testing.B) {
+	board, err := NewBoard(17, 9)
+	if err != nil {
+		b.Fatal(err)
+	}
+
 	data := []byte{0x9b, 0x4c, 0x7b, 0xce, 0x7a, 0xbd, 0x0a, 0x13, 0x61, 0xfb, 0x17, 0xc2, 0x06, 0x12, 0x0c, 0xed}
-	board := NewBoard(17, 9)
 	board.Write(data)
 
 	for _, ts := range BundledTileSets {
@@ -202,8 +248,12 @@ func BenchmarkBoard_Render(b *testing.B) {
 }
 
 func BenchmarkArmor(b *testing.B) {
+	board, err := NewBoard(17, 9)
+	if err != nil {
+		b.Fatal(err)
+	}
+
 	data := []byte{0x9b, 0x4c, 0x7b, 0xce, 0x7a, 0xbd, 0x0a, 0x13, 0x61, 0xfb, 0x17, 0xc2, 0x06, 0x12, 0x0c, 0xed}
-	board := NewBoard(17, 9)
 	board.Write(data)
 	raw := board.Render(SSHTiles)
 

example/fcaddr/fcaddr.go

@@ -88,7 +88,11 @@ func main() {
 	fmt.Printf("decoded: 0x%x (%v bytes) / checksum: 0x%x (%v bytes)\n", hsh, len(hsh), checksum, len(checksum))
 
 	// display!
-	board := randomart.NewBoard(int(*width), int(*height))
+	board, err := randomart.NewBoard(int(*width), int(*height))
+	if err != nil {
+		log.Fatal(err)
+	}
+
 	board.Write((hsh))
 	fmt.Printf("%s", board.Render(tileset))
 }