1 files changed, 43 insertions, 0 deletions
diff --git a/internal/tui/dashboard/sparkline_test.go b/internal/tui/dashboard/sparkline_test.go
new file mode 100644
index 0000000..d39d145
--- /dev/null
+++ b/internal/tui/dashboard/sparkline_test.go
@@ -0,0 +1,43 @@
+package dashboard
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestRenderSparklineEmptyOrInvalidWidth(t *testing.T) {
+	if got := renderSparkline(nil, 5); got != "" {
+		t.Fatalf("expected empty sparkline for nil data, got %q", got)
+	}
+	if got := renderSparkline([]float64{1, 2, 3}, 0); got != "" {
+		t.Fatalf("expected empty sparkline for width 0, got %q", got)
+	}
+}
+
+func TestRenderSparklineSingleValue(t *testing.T) {
+	got := renderSparkline([]float64{10}, 8)
+	if got != "▄" {
+		t.Fatalf("expected single mid-bar rune, got %q", got)
+	}
+}
+
+func TestRenderSparklineAllEqualValues(t *testing.T) {
+	got := renderSparkline([]float64{5, 5, 5, 5}, 4)
+	if got != "▄▄▄▄" {
+		t.Fatalf("expected flat sparkline, got %q", got)
+	}
+}
+
+func TestRenderSparklineRespectsWidthTruncation(t *testing.T) {
+	got := renderSparkline([]float64{1, 2, 3, 4, 5, 6, 7, 8}, 4)
+	if len([]rune(got)) != 4 {
+		t.Fatalf("expected 4 runes, got %q", got)
+	}
+}
+
+func TestRenderSparklineSpansLowToHigh(t *testing.T) {
+	got := renderSparkline([]float64{0, 10}, 2)
+	if !strings.Contains(got, "▁") || !strings.Contains(got, "█") {
+		t.Fatalf("expected low/high bars, got %q", got)
+	}
+}