more test setup

internal/viewport/linebuffer/linebuffer.go

@@ -1,6 +1,7 @@
 package linebuffer
 
 import (
+	"fmt"
 	"github.com/charmbracelet/lipgloss/v2"
 	"github.com/mattn/go-runewidth"
 	"github.com/robinovitch61/kl/internal/constants"
@@ -77,6 +78,10 @@ func New(line string) *LineBuffer {
 	return &lb
 }
 
+func (l LineBuffer) Repr() string {
+	return fmt.Sprintf("LB(%q)", l.content)
+}
+
 func (l LineBuffer) Width() int {
 	if len(l.lineNoAnsiCumWidths) > 0 {
 		return int(l.lineNoAnsiCumWidths[len(l.lineNoAnsiCumWidths)-1])

internal/viewport/linebuffer/linebufferer.go

@@ -3,6 +3,7 @@ package linebuffer
 import "github.com/charmbracelet/lipgloss/v2"
 
 type LineBufferer interface {
+	Repr() string
 	Width() int
 	Content() string
 	SeekToWidth(width int)

internal/viewport/linebuffer/multilinebuffer.go

@@ -1,6 +1,8 @@
 package linebuffer
 
-import "github.com/charmbracelet/lipgloss/v2"
+import (
+	"github.com/charmbracelet/lipgloss/v2"
+)
 
 // MultiLineBuffer implements LineBufferer by wrapping multiple LineBuffers without extra memory allocation
 type MultiLineBuffer struct {
@@ -28,11 +30,24 @@ func NewMulti(buffers ...*LineBuffer) *MultiLineBuffer {
 	}
 }
 
+func (m MultiLineBuffer) Repr() string {
+	v := "Multi("
+	for i := range m.buffers {
+		if i > 0 {
+			v += ", "
+		}
+		v += m.buffers[i].Repr()
+	}
+	v += ")"
+	return v
+}
+
 func (m *MultiLineBuffer) Width() int {
 	return m.totalWidth
 }
 
 // TODO LEO: don't use this for e.g. search, instead inject filter into a Matches() bool method here
+// TODO LEO: or store the concatenated string on init?
 func (m *MultiLineBuffer) Content() string {
 	totalLen := 0
 	for _, buf := range m.buffers {

internal/viewport/linebuffer/multlinebuffer_test.go

@@ -1,9 +1,12 @@
 package linebuffer
 
-import "testing"
+import (
+	"github.com/charmbracelet/lipgloss/v2"
+	"testing"
+)
 
-var equivalentLineBuffers = [][]LineBufferer{
-	{
+var equivalentLineBuffers = map[string][]LineBufferer{
+	"hello world": {
 		New("hello world"),
 		NewMulti(
 			New("hello"),
@@ -31,6 +34,16 @@ var equivalentLineBuffers = [][]LineBufferer{
 	},
 }
 
+func TestMultiLineBuffer_Width(t *testing.T) {
+	for _, eq := range equivalentLineBuffers {
+		for i, lb := range eq {
+			if lb.Width() != eq[0].Width() {
+				t.Errorf("expected %d, got %d for line buffer %d", eq[0].Width(), lb.Width(), i)
+			}
+		}
+	}
+}
+
 func TestMultiLineBuffer_Content(t *testing.T) {
 	for _, eq := range equivalentLineBuffers {
 		for i, lb := range eq {
@@ -41,4 +54,35 @@ func TestMultiLineBuffer_Content(t *testing.T) {
 	}
 }
 
+func TestMultiLineBuffer_SeekToWidth(t *testing.T) {
+	tests := []struct {
+		name            string
+		key             string
+		seekToWidth     int
+		takeWidth       int
+		continuation    string
+		expectedPopLeft string
+	}{
+		{
+			name:            "hello world 0",
+			key:             "hello world",
+			seekToWidth:     0,
+			takeWidth:       7,
+			continuation:    "",
+			expectedPopLeft: "hello w",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			for _, eq := range equivalentLineBuffers[tt.key] {
+				eq.SeekToWidth(tt.seekToWidth)
+				if actual := eq.PopLeft(tt.takeWidth, tt.continuation, "", lipgloss.NewStyle()); actual != tt.expectedPopLeft {
+					t.Errorf("for %s, expected %q, got %q", eq.Repr(), tt.expectedPopLeft, actual)
+				}
+			}
+		})
+	}
+}
+
 //func TestMultiLin