Improve handling of version flag

* Only use/show builtin `--version` flag if args are versioned with a non-empty `Version()`
* If args define a `--version` flag, honor it and disable/hide the builtin version flag
* Only return `ErrVersion` when using the builtin version flag

1 files changed, 46 insertions, 2 deletions

diff --git a/parse_test.go b/parse_test.go
index 77a034f..06e7a76 100644
--- a/parse_test.go
+++ b/parse_test.go
@@ -1380,11 +1380,55 @@ func TestReuseParser(t *testing.T) {
 	assert.Error(t, err)
 }
 
-func TestVersion(t *testing.T) {
+func TestNoVersion(t *testing.T) {
 	var args struct{}
-	err := parse("--version", &args)
+
+	p, err := NewParser(Config{}, &args)
+	require.NoError(t, err)
+
+	err = p.Parse([]string{"--version"})
+	assert.Error(t, err)
+	assert.NotEqual(t, ErrVersion, err)
+}
+
+func TestBuiltinVersion(t *testing.T) {
+	var args struct{}
+
+	p, err := NewParser(Config{}, &args)
+	require.NoError(t, err)
+
+	p.version = "example 3.2.1"
+
+	err = p.Parse([]string{"--version"})
 	assert.Equal(t, ErrVersion, err)
+}
 
+func TestArgsVersion(t *testing.T) {
+	var args struct {
+		Version bool `arg:"--version"`
+	}
+
+	p, err := NewParser(Config{}, &args)
+	require.NoError(t, err)
+
+	err = p.Parse([]string{"--version"})
+	require.NoError(t, err)
+	require.Equal(t, args.Version, true)
+}
+
+func TestArgsAndBuiltinVersion(t *testing.T) {
+	var args struct {
+		Version bool `arg:"--version"`
+	}
+
+	p, err := NewParser(Config{}, &args)
+	require.NoError(t, err)
+
+	p.version = "example 3.2.1"
+
+	err = p.Parse([]string{"--version"})
+	require.NoError(t, err)
+	require.Equal(t, args.Version, true)
 }
 
 func TestMultipleTerminates(t *testing.T) {