Port the fish setup function to Go

tools/tui/shell_integration/api_test.go

@@ -0,0 +1,42 @@
+// License: GPLv3 Copyright: 2023, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package shell_integration
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+var _ = fmt.Print
+
+func TestExtractShellIntegration(t *testing.T) {
+	tdir := t.TempDir()
+	if err := extract_shell_integration_for("zsh", tdir); err != nil {
+		t.Fatal(err)
+	}
+	kzsh := filepath.Join(tdir, "shell-integration", "zsh", "kitty.zsh")
+	if _, err := os.Stat(kzsh); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Stat(filepath.Join(tdir, "shell-integration", "zsh", "completions", "_kitty")); err != nil {
+		t.Fatal(err)
+	}
+	orig, err := os.ReadFile(kzsh)
+	if err != nil {
+		t.Fatal(err)
+	}
+	os.WriteFile(kzsh, []byte("changed"), 0o644)
+	if err := extract_shell_integration_for("zsh", tdir); err != nil {
+		t.Fatal(err)
+	}
+	changed, err := os.ReadFile(kzsh)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(changed, orig) {
+		t.Fatalf("Failed to update shell integration file")
+	}
+}