feat(test): Add unit tests for all themes

Use Tmux itself by spinning up a temporary test server, load the theme,
and use "show-options" to pull out and validate relevant options that
are set by the theme.

test/basic_test.go

@@ -0,0 +1,47 @@
+package test
+
+import (
+	"testing"
+
+	"github.com/jimeh/go-tmux"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestBasicTheme(t *testing.T) {
+	tmuxSetup()
+	defer tmuxTearDown()
+
+	theme := "../basic.tmuxtheme"
+
+	_, err := tm.Exec("source-file", theme)
+	assert.NoErrorf(t, err, `%s: Failed to load theme`, theme)
+
+	tmuxHasOptions(t, theme, tmux.GlobalWindow, tmux.Options{
+		"clock-mode-colour":            "red",
+		"clock-mode-style":             "24",
+		"mode-style":                   "bg=red",
+		"pane-active-border-style":     "fg=green",
+		"pane-border-style":            "default",
+		"window-status-activity-style": "fg=yellow,bg=black",
+		"window-status-current-format": " #I:#W#F ",
+		"window-status-current-style":  "fg=black,bg=red",
+		"window-status-format":         " #I:#W#F ",
+		"window-status-separator":      "",
+	})
+
+	tmuxHasOptions(t, theme, tmux.GlobalSession, tmux.Options{
+		"display-panes-active-colour": "default",
+		"display-panes-colour":        "default",
+		"message-command-style":       "default",
+		"message-style":               "default",
+		"status-interval":             "1",
+		"status-justify":              "centre",
+		"status-left":                 "#S #[fg=white]» #[fg=yellow]#I #[fg=cyan]#P",
+		"status-left-length":          "40",
+		"status-left-style":           "fg=green,bg=black",
+		"status-right":                "#H #[fg=white]« #[fg=yellow]%H:%M:%S #[fg=green]%d-%b-%y",
+		"status-right-length":         "40",
+		"status-right-style":          "fg=cyan,bg=black",
+		"status-style":                "fg=cyan,bg=black",
+	})
+}