Fix chat redraw and input history

uiterm/textview_test.go

@@ -0,0 +1,46 @@
+package uiterm
+
+import "testing"
+
+func TestTextviewVisibleStartLineShowsBottomWhenNotScrolled(t *testing.T) {
+	t.Parallel()
+
+	textview := Textview{
+		parsedLines: []string{"one", "two", "three", "four"},
+	}
+
+	if got := textview.visibleStartLine(3); got != 1 {
+		t.Fatalf("expected visible lines to start at 1, got %d", got)
+	}
+}
+
+func TestTextviewVisibleStartLineHonorsScrollOffset(t *testing.T) {
+	t.Parallel()
+
+	textview := Textview{
+		CurrentLine: 2,
+		parsedLines: []string{"one", "two", "three", "four", "five"},
+	}
+
+	if got := textview.visibleStartLine(3); got != 0 {
+		t.Fatalf("expected scrolled view to start at 0, got %d", got)
+	}
+}
+
+func TestTextviewUpdateParsedLinesClampsScrollOffset(t *testing.T) {
+	t.Parallel()
+
+	textview := Textview{
+		CurrentLine:    10,
+		Lines:          []string{"one", "two"},
+		showTimestamps: true,
+		x0:             0,
+		x1:             20,
+	}
+
+	textview.updateParsedLines()
+
+	if textview.CurrentLine != 1 {
+		t.Fatalf("expected current line to clamp to 1, got %d", textview.CurrentLine)
+	}
+}