cmd/wit-bindgen-wrpc: adds -v flag for enabling stderr output

This commit adds a `--verbose`/`-v` for enable output to stderr for
the `wit-bindgen-wrpc` binary

Fixes #214

Signed-off-by: Victor Adossi <[email protected]>

cmd/wit-bindgen-go/.gitignore

@@ -0,0 +1 @@
+wit-bindgen-go

cmd/wit-bindgen-go/cmd/generate/generate.go

@@ -3,6 +3,7 @@ package generate
 import (
 	"context"
 	"fmt"
+	"log"
 	"os"
 	"path/filepath"
 	"strings"
@@ -75,6 +76,7 @@ type config struct {
 	versioned bool
 	forceWIT  bool
 	path      string
+	verbose   bool
 }
 
 func action(ctx context.Context, cmd *cli.Command) error {
@@ -140,25 +142,35 @@ func parseFlags(cmd *cli.Command) (*config, error) {
 		cmd.Bool("versioned"),
 		cmd.Bool("force-wit"),
 		path,
+		cmd.Bool("verbose"),
 	}, nil
 }
 
+// Generate and write the specified Go packages w/ provided bindgen config
+//
+// Parameters:
+//   - packages: A slice of pointers to `gen.Package`s to generate
+//   - cfg: A pointer to a `config` struct
+//
+// Returns:
+//   - error: An error if the package writing process fails, or nil if all
+//     packages are written successfully.
 func writeGoPackages(packages []*gen.Package, cfg *config) error {
-	fmt.Fprintf(os.Stderr, "Generated %d package(s)\n", len(packages))
+	log.Printf("Generated %d package(s)\n", len(packages))
 	for _, pkg := range packages {
 		if !pkg.HasContent() {
-			fmt.Fprintf(os.Stderr, "Skipping empty package: %s\n", pkg.Path)
+			log.Printf("Skipping empty package: %s\n", pkg.Path)
 			continue
 		}
-		fmt.Fprintf(os.Stderr, "Generated package: %s\n", pkg.Path)
+		log.Printf("Generated package: %s\n", pkg.Path)
 
 		for _, filename := range codec.SortedKeys(pkg.Files) {
 			file := pkg.Files[filename]
 			dir := filepath.Join(cfg.out, strings.TrimPrefix(file.Package.Path, cfg.pkgRoot))
 			path := filepath.Join(dir, file.Name)
 
 			if !file.HasContent() {
-				fmt.Fprintf(os.Stderr, "Skipping empty file: %s\n", path)
+				log.Printf("Skipping empty file: %s\n", path)
 				continue
 			}
 
@@ -171,9 +183,9 @@ func writeGoPackages(packages []*gen.Package, cfg *config) error {
 				if content == nil {
 					return err
 				}
-				fmt.Fprintf(os.Stderr, "Error formatting file: %v\n", err)
+				log.Printf("Error formatting file: %v\n", err)
 			} else {
-				fmt.Fprintf(os.Stderr, "Generated file: %s\n", path)
+				log.Printf("Generated file: %s\n", path)
 			}
 
 			if cfg.dryRun {

cmd/wit-bindgen-go/main.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"log"
+	"io"
 	"runtime/debug"
 
 	"github.com/urfave/cli/v3"
@@ -39,8 +41,9 @@ func init() {
 	}
 }
 
-func main() {
-	cmd := &cli.Command{
+// Generate the app
+func makeCmd() cli.Command {
+	cmd := cli.Command{
 		Name:  "wit-bindgen-go",
 		Usage: "inspect or manipulate WebAssembly Interface Types for Go",
 		Commands: []*cli.Command{
@@ -55,6 +58,18 @@ func main() {
 		},
 		Version: versionString,
 	}
+	return cmd
+}
+
+func main() {
+	cmd := makeCmd()
+
+	// If verbose was specified, use set global logger appropriately
+	if cmd.Bool("verbose") {
+		log.SetOutput(os.Stderr)
+	} else {
+		log.SetOutput(io.Discard)
+	}
 
 	err := cmd.Run(context.Background(), os.Args)
 	if err != nil {

cmd/wit-bindgen-go/main_test.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"testing"
+)
+
+// TestSimpleGenVerbosity ensures that a basic generation case honors the verbose flag
+func TestSimpleGenVerbosity(t *testing.T) {
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+	cmd := makeCmd()
+	cmd.Writer = &stdout
+	cmd.ErrWriter = &stderr
+
+	args := []string{
+		"wit-bindgen-go",
+		"generate",
+		"--world",
+		"http-fetch-simple",
+		"--dry-run",
+		"../../testdata/codegen/simple-http.wit",
+	}
+
+	// Run the app without verbose
+	cmd.Run(context.Background(), args)
+	if stderr.Len() != 0 {
+		t.Errorf("output was written to stderr despite lack of --verbose")
+	}
+
+	stdout.Reset()
+	stderr.Reset()
+
+	// Run the app WITH verbose
+	cmd.Run(context.Background(), append(args, "--verbose"))
+	if stderr.Len() == 0 {
+		t.Errorf("no output was written to stderr when --verbose was used")
+	}
+}