fix: border size getters when implicit borders are present

borders.go

@@ -228,11 +228,6 @@ func HiddenBorder() Border {
 
 func (s Style) applyBorder(str string) string {
 	var (
-		topSet    = s.isSet(borderTopKey)
-		rightSet  = s.isSet(borderRightKey)
-		bottomSet = s.isSet(borderBottomKey)
-		leftSet   = s.isSet(borderLeftKey)
-
 		border    = s.getBorderStyle()
 		hasTop    = s.getAsBool(borderTopKey, false)
 		hasRight  = s.getAsBool(borderRightKey, false)
@@ -252,7 +247,7 @@ func (s Style) applyBorder(str string) string {
 
 	// If a border is set and no sides have been specifically turned on or off
 	// render borders on all sides.
-	if border != noBorder && !(topSet || rightSet || bottomSet || leftSet) {
+	if s.implicitBorders() {
 		hasTop = true
 		hasRight = true
 		hasBottom = true

borders_test.go

@@ -0,0 +1,96 @@
+package lipgloss
+
+import "testing"
+
+func TestStyle_GetBorderSizes(t *testing.T) {
+	tests := []struct {
+		name  string
+		style Style
+		wantX int
+		wantY int
+	}{
+		{
+			name:  "Default style",
+			style: NewStyle(),
+			wantX: 0,
+			wantY: 0,
+		},
+		{
+			name:  "Border(NormalBorder())",
+			style: NewStyle().Border(NormalBorder()),
+			wantX: 2,
+			wantY: 2,
+		},
+		{
+			name:  "Border(NormalBorder(), true)",
+			style: NewStyle().Border(NormalBorder(), true),
+			wantX: 2,
+			wantY: 2,
+		},
+		{
+			name:  "Border(NormalBorder(), true, false)",
+			style: NewStyle().Border(NormalBorder(), true, false),
+			wantX: 0,
+			wantY: 2,
+		},
+		{
+			name:  "Border(NormalBorder(), true, true, false)",
+			style: NewStyle().Border(NormalBorder(), true, true, false),
+			wantX: 2,
+			wantY: 1,
+		},
+		{
+			name:  "Border(NormalBorder(), true, true, false, false)",
+			style: NewStyle().Border(NormalBorder(), true, true, false, false),
+			wantX: 1,
+			wantY: 1,
+		},
+		{
+			name:  "BorderTop(true).BorderStyle(NormalBorder())",
+			style: NewStyle().BorderTop(true).BorderStyle(NormalBorder()),
+			wantX: 0,
+			wantY: 1,
+		},
+		{
+			name:  "BorderStyle(NormalBorder())",
+			style: NewStyle().BorderStyle(NormalBorder()),
+			wantX: 2,
+			wantY: 2,
+		},
+		{
+			name:  "Custom BorderStyle",
+			style: NewStyle().BorderStyle(Border{Left: "123456789"}),
+			wantX: 1, // left and right borders are laid out vertically, one rune per row
+			wantY: 0,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gotX := tt.style.GetHorizontalBorderSize()
+			if gotX != tt.wantX {
+				t.Errorf("Style.GetHorizontalBorderSize() got %d, want %d", gotX, tt.wantX)
+			}
+
+			gotY := tt.style.GetVerticalBorderSize()
+			if gotY != tt.wantY {
+				t.Errorf("Style.GetVerticalBorderSize() got %d, want %d", gotY, tt.wantY)
+			}
+
+			gotX = tt.style.GetHorizontalFrameSize()
+			if gotX != tt.wantX {
+				t.Errorf("Style.GetHorizontalFrameSize() got %d, want %d", gotX, tt.wantX)
+			}
+
+			gotY = tt.style.GetVerticalFrameSize()
+			if gotY != tt.wantY {
+				t.Errorf("Style.GetVerticalFrameSize() got %d, want %d", gotY, tt.wantY)
+			}
+
+			gotX, gotY = tt.style.GetFrameSize()
+			if gotX != tt.wantX || gotY != tt.wantY {
+				t.Errorf("Style.GetFrameSize() got (%d, %d), want (%d, %d)", gotX, gotY, tt.wantX, tt.wantY)
+			}
+		})
+	}
+}

get.go

@@ -300,7 +300,7 @@ func (s Style) GetBorderTopWidth() int {
 // runes of varying widths, the widest rune is returned. If no border exists on
 // the top edge, 0 is returned.
 func (s Style) GetBorderTopSize() int {
-	if !s.getAsBool(borderTopKey, false) {
+	if !s.getAsBool(borderTopKey, false) && !s.implicitBorders() {
 		return 0
 	}
 	return s.getBorderStyle().GetTopSize()
@@ -310,7 +310,7 @@ func (s Style) GetBorderTopSize() int {
 // runes of varying widths, the widest rune is returned. If no border exists on
 // the left edge, 0 is returned.
 func (s Style) GetBorderLeftSize() int {
-	if !s.getAsBool(borderLeftKey, false) {
+	if !s.getAsBool(borderLeftKey, false) && !s.implicitBorders() {
 		return 0
 	}
 	return s.getBorderStyle().GetLeftSize()
@@ -320,7 +320,7 @@ func (s Style) GetBorderLeftSize() int {
 // contain runes of varying widths, the widest rune is returned. If no border
 // exists on the left edge, 0 is returned.
 func (s Style) GetBorderBottomSize() int {
-	if !s.getAsBool(borderBottomKey, false) {
+	if !s.getAsBool(borderBottomKey, false) && !s.implicitBorders() {
 		return 0
 	}
 	return s.getBorderStyle().GetBottomSize()
@@ -330,7 +330,7 @@ func (s Style) GetBorderBottomSize() int {
 // contain runes of varying widths, the widest rune is returned. If no border
 // exists on the right edge, 0 is returned.
 func (s Style) GetBorderRightSize() int {
-	if !s.getAsBool(borderRightKey, false) {
+	if !s.getAsBool(borderRightKey, false) && !s.implicitBorders() {
 		return 0
 	}
 	return s.getBorderStyle().GetRightSize()
@@ -519,6 +519,20 @@ func (s Style) getBorderStyle() Border {
 	return s.borderStyle
 }
 
+// Returns whether or not the style has implicit borders. This happens when
+// a border style has been set but no border sides have been explicitly turned
+// on or off.
+func (s Style) implicitBorders() bool {
+	var (
+		borderStyle = s.getBorderStyle()
+		topSet      = s.isSet(borderTopKey)
+		rightSet    = s.isSet(borderRightKey)
+		bottomSet   = s.isSet(borderBottomKey)
+		leftSet     = s.isSet(borderLeftKey)
+	)
+	return borderStyle != noBorder && !(topSet || rightSet || bottomSet || leftSet)
+}
+
 func (s Style) getAsTransform(propKey) func(string) string {
 	if !s.isSet(transformKey) {
 		return nil