feat: add versioning

cli_test.go

@@ -2,10 +2,34 @@ package main
 
 import (
 	"bytes"
+	"regexp"
 	"strings"
 	"testing"
 )
 
+func TestVersionCommandPrintsSemanticVersion(t *testing.T) {
+	var output bytes.Buffer
+	handled, err := handleVersionCommand([]string{"--version"}, &output)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !handled || output.String() != "diple "+dipleVersion+"\n" {
+		t.Fatalf("version output = %q, handled=%t", output.String(), handled)
+	}
+	if !regexp.MustCompile(`^0\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)$`).MatchString(dipleVersion) {
+		t.Fatalf("version %q is not a pre-1.0 semantic version", dipleVersion)
+	}
+}
+
+func TestVersionCommandRejectsAdditionalArguments(t *testing.T) {
+	handled, err := handleVersionCommand(
+		[]string{"--version", "--help"}, &bytes.Buffer{},
+	)
+	if !handled || err == nil || !strings.Contains(err.Error(), "usage: diple --version") {
+		t.Fatalf("handled=%t error=%v", handled, err)
+	}
+}
+
 func TestCompletionCommandGeneratesSupportedShells(t *testing.T) {
 	for _, shell := range completionShells {
 		t.Run(shell, func(t *testing.T) {
@@ -65,6 +89,7 @@ func TestCLIHelpIsGroupedAndActionable(t *testing.T) {
 		"Appearance and navigation:",
 		"Local state:",
 		"diple completion <bash|zsh|fish>",
+		"--version",
 		"--repo OWNER/REPOSITORY",
 		"--cache=false",
 		"gh auth login",