1 files changed, 22 insertions, 0 deletions
diff --git a/internal/tui/tui_test.go b/internal/tui/tui_test.go
index a3640ac..614f239 100644
--- a/internal/tui/tui_test.go
+++ b/internal/tui/tui_test.go
@@ -51,6 +51,28 @@ func TestHeight(t *testing.T) {
 	}
 }
 
+// TestWidth: the terminal's column count, and 0 wherever there is no
+// terminal to wrap to, so a caller treats 0 as "never wrap".
+func TestWidth(t *testing.T) {
+	var buf bytes.Buffer
+	if w := Width(&buf); w != 0 {
+		t.Errorf("Width on a non-terminal writer = %d, want 0", w)
+	}
+
+	oldT, oldS := isTerminal, termSize
+	t.Cleanup(func() { isTerminal, termSize = oldT, oldS })
+	isTerminal = func(fd int) bool { return true }
+	termSize = func(fd int) (int, int, error) { return 132, 24, nil }
+	if w := Width(os.Stdout); w != 132 {
+		t.Errorf("Width = %d, want 132", w)
+	}
+
+	termSize = func(fd int) (int, int, error) { return 0, 0, os.ErrInvalid }
+	if w := Width(os.Stdout); w != 0 {
+		t.Errorf("Width when the size cannot be read = %d, want 0", w)
+	}
+}
+
 func TestPageUsesPagerOnlyWhenTaller(t *testing.T) {
 	dir := t.TempDir()
 	marker := filepath.Join(dir, "paged")