feat(envc): add support for converting current process environment to YAML

Enhance the `envc convert` command to allow conversion of the current process environment to YAML format. Update README with usage examples and clarify input options. Add tests to ensure correct functionality for environment variable handling.

cmd/envc/convert.go

@@ -22,7 +22,7 @@ func RunConvert(args []string, stdin io.Reader, stdout, stderr io.Writer) int {
 	fs.SetOutput(stderr)
 	from := fs.String("from", "", "source format: yaml|json|toml|ini|env")
 	to := fs.String("to", "", "target format: yaml|json|toml|ini|env")
-	input := fs.String("input", "-", "input path, URL, or - for stdin")
+	input := fs.String("input", "-", "input path, URL, - for stdin, or \"environ\" for current process env (requires --from env)")
 	output := fs.String("output", "-", "output path or - for stdout")
 	if err := fs.Parse(args); err != nil {
 		return 2
@@ -32,16 +32,31 @@ func RunConvert(args []string, stdin io.Reader, stdout, stderr io.Writer) int {
 		return 2
 	}
 	ctx := context.Background()
-	src := openSource(*input, stdin)
-	b, err := bytesutil.ReadAll(ctx, src)
-	if err != nil {
-		_, _ = fmt.Fprintf(stderr, "convert: read: %v\n", err)
-		return 1
-	}
-	m, err := loadMapFromBytes(ctx, *from, b)
-	if err != nil {
-		_, _ = fmt.Fprintf(stderr, "convert: parse: %v\n", err)
-		return 1
+	var m map[string]any
+	var err error
+	if *input == "environ" {
+		if *from != "env" {
+			_, _ = fmt.Fprintln(stderr, "convert: --input environ only works with --from env")
+			return 2
+		}
+		m, err = env.New(env.WithCurrentEnvironment()).Map(ctx)
+		if err != nil {
+			_, _ = fmt.Fprintf(stderr, "convert: environ: %v\n", err)
+			return 1
+		}
+	} else {
+		src := openSource(*input, stdin)
+		var b []byte
+		b, err = bytesutil.ReadAll(ctx, src)
+		if err != nil {
+			_, _ = fmt.Fprintf(stderr, "convert: read: %v\n", err)
+			return 1
+		}
+		m, err = loadMapFromBytes(ctx, *from, b)
+		if err != nil {
+			_, _ = fmt.Fprintf(stderr, "convert: parse: %v\n", err)
+			return 1
+		}
 	}
 	outb, err := marshalMap(*to, m)
 	if err != nil {

cmd/envc/convert_test.go

@@ -8,6 +8,33 @@ import (
 	"testing"
 )
 
+func TestRunConvert_EnvironToYAML(t *testing.T) {
+	t.Setenv("ENVC_TEST_PUBLISH", "xyzzy")
+	var stdout, stderr bytes.Buffer
+	code := RunConvert([]string{
+		"--from", "env", "--to", "yaml",
+		"--input", "environ", "--output", "-",
+	}, strings.NewReader(""), &stdout, &stderr)
+	if code != 0 {
+		t.Fatalf("stderr: %s", stderr.String())
+	}
+	out := stdout.String()
+	if !strings.Contains(out, "xyzzy") {
+		t.Fatalf("expected value in yaml out: %s", out)
+	}
+}
+
+func TestRuknConvert_EnvironRequiresFromEnv(t *testing.T) {
+	var stdout, stderr bytes.Buffer
+	code := RunConvert([]string{
+		"--from", "yaml", "--to", "json",
+		"--input", "environ", "--output", "-",
+	}, strings.NewReader(""), &stdout, &stderr)
+	if code != 2 {
+		t.Fatalf("expected exit 2, got %d stderr=%s", code, stderr.String())
+	}
+}
+
 func TestRunConvert_TOMLToJSON(t *testing.T) {
 	var stdout, stderr bytes.Buffer
 	stdin := strings.NewReader("[app]\nport = 8080\n")