🐛 Remove use of upstream package global variable

The upstream package which detected and set background colour was using
a global variable which was cached. Tests relying on different states
were giving incorrect results.

Replaced lipgloss detection with termenv (which lipgloss uses) and
instantiated a new output to do detection against.

internal/ui/theme/theme.go

@@ -1,10 +1,13 @@
 package theme
 
 import (
+	"io"
+
 	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/lipgloss"
 	tint "github.com/lrstanley/bubbletint"
 	"github.com/mikelorant/committed/internal/config"
+	"github.com/muesli/termenv"
 )
 
 type Theme struct {
@@ -25,7 +28,7 @@ func New(clr config.Colour) Theme {
 		lipgloss.SetHasDarkBackground(false)
 		t = lightTints()
 	default:
-		switch lipgloss.HasDarkBackground() {
+		switch termenv.NewOutput(io.Discard).HasDarkBackground() {
 		case true:
 			t = darkTints()
 		case false:

internal/ui/theme/theme_test.go

@@ -75,32 +75,32 @@ func TestNextTint(t *testing.T) {
 	}{
 		{
 			name: "first",
-			id:   "builtin_light",
+			id:   "builtin_dark",
 		},
 		{
 			name:  "one",
 			count: 1,
-			id:    "builtin_solarized_light",
+			id:    "dracula",
 		},
 		{
 			name:  "three",
-			count: 3,
-			id:    "gruvbox_light",
+			count: 4,
+			id:    "retrowave",
 		},
 		{
 			name:  "last",
-			count: 4,
-			id:    "tokyo_night_light",
+			count: 6,
+			id:    "tokyo_night",
 		},
 		{
 			name:  "last_plus_one",
-			count: 5,
-			id:    "builtin_light",
+			count: 7,
+			id:    "builtin_dark",
 		},
 		{
 			name:  "last_plus_two",
-			count: 6,
-			id:    "builtin_solarized_light",
+			count: 8,
+			id:    "dracula",
 		},
 	}
 
@@ -125,11 +125,13 @@ func TestListTints(t *testing.T) {
 		{
 			name: "default",
 			want: []string{
-				"builtin_light",
-				"builtin_solarized_light",
-				"builtin_tango_light",
-				"gruvbox_light",
-				"tokyo_night_light",
+				"builtin_dark",
+				"dracula",
+				"gruvbox_dark",
+				"nord",
+				"retrowave",
+				"solarized_dark_higher_contrast",
+				"tokyo_night",
 			},
 		},
 	}
@@ -152,13 +154,13 @@ func TestGetTint(t *testing.T) {
 	}{
 		{
 			name: "valid",
-			id:   "builtin_light",
-			want: "builtin_light",
+			id:   "builtin_dark",
+			want: "builtin_dark",
 		},
 		{
 			name: "invalid",
 			id:   "invalid",
-			want: "builtin_light",
+			want: "builtin_dark",
 		},
 	}
 
@@ -187,17 +189,17 @@ func TestSetTint(t *testing.T) {
 	}{
 		{
 			name: "valid",
-			id:   "builtin_tango_light",
+			id:   "dracula",
 			want: want{
-				id: "builtin_tango_light",
+				id: "dracula",
 				ok: true,
 			},
 		},
 		{
 			name: "invalid",
 			id:   "test",
 			want: want{
-				id: "builtin_light",
+				id: "builtin_dark",
 			},
 		},
 	}