feat: add stdout output support to avrogen

README.md

@@ -176,6 +176,8 @@ Example usage assuming there's a valid schema in `in.avsc`:
 avrogen -pkg avro -o bla.go -tags json:snake,yaml:upper-camel in.avsc
 ```
 
+**Tip:** Omit `-o FILE` to dump the generated Go structs to stdout instead of a file.
+
 Check the options and usage with `-h`:
 
 ```shell

cmd/avrogen/main.go

@@ -23,15 +23,15 @@ type config struct {
 }
 
 func main() {
- os.Exit(realMain(os.Args, os.Stderr))
+ os.Exit(realMain(os.Args, os.Stderr, os.Stdout))
 }
 
-func realMain(args []string, out io.Writer) int {
+func realMain(args []string, out, dumpout io.Writer) int {
  var cfg config
  flgs := flag.NewFlagSet("avrogen", flag.ExitOnError)
  flgs.SetOutput(out)
  flgs.StringVar(&cfg.Pkg, "pkg", "", "The package name of the output file.")
- flgs.StringVar(&cfg.Out, "o", "", "The output file path.")
+ flgs.StringVar(&cfg.Out, "o", "", "The output file path (dump to stdout if not provided).")
  flgs.StringVar(&cfg.Tags, "tags", "", "The additional field tags <tag-name>:{snake|camel|upper-camel|kebab}>[,...]")
  flgs.BoolVar(&cfg.FullName, "fullname", false, "Use the full name of the Record schema to create the struct name.")
  flgs.BoolVar(&cfg.Encoders, "encoders", false, "Generate encoders for the structs.")
@@ -75,12 +75,20 @@ func realMain(args []string, out io.Writer) int {
  }
  formatted, err := format.Source(buf.Bytes())
  if err != nil {
- _, _ = fmt.Fprintf(out, "Error: could format code: %v\n", err)
+ _, _ = fmt.Fprintf(out, "Error: could not format code: %v\n", err)
  return 3
  }
- if err = os.WriteFile(cfg.Out, formatted, 0o600); err != nil {
- _, _ = fmt.Fprintf(out, "Error: could write file: %v\n", err)
- return 4
+
+ if cfg.Out == "" {
+ if _, err = dumpout.Write(formatted); err != nil {
+ _, _ = fmt.Fprintf(out, "Error: could not write to stdout: %v\n", err)
+ return 4
+ }
+ } else {
+ if err = os.WriteFile(cfg.Out, formatted, 0o600); err != nil {
+ _, _ = fmt.Fprintf(out, "Error: could not write file: %v\n", err)
+ return 4
+ }
  }
  return 0
 }
@@ -94,10 +102,6 @@ func validateOpts(nargs int, cfg config) error {
  return fmt.Errorf("a package is required")
  }
 
- if cfg.Out == "" {
- return fmt.Errorf("an output file is reqired")
- }
-
  return nil
 }
 

cmd/avrogen/main_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+ "bytes"
  "flag"
  "io"
  "os"
@@ -34,11 +35,6 @@ func TestAvroGen_RequiredFlags(t *testing.T) {
  args: []string{"avrogen", "-o", "some/file", "schema.avsc"},
  wantErr: true,
  },
- {
- name: "validates output file is set",
- args: []string{"avrogen", "-pkg", "test", "schema.avsc"},
- wantErr: true,
- },
  {
  name: "validates tag format are valid",
  args: []string{"avrogen", "-o", "some/file", "-pkg", "test", "-tags", "snake", "schema.avsc"},
@@ -59,7 +55,7 @@ func TestAvroGen_RequiredFlags(t *testing.T) {
  for _, test := range tests {
  test := test
  t.Run(test.name, func(t *testing.T) {
- got := realMain(test.args, io.Discard)
+ got := realMain(test.args, io.Discard, io.Discard)
 
  if !test.wantErr {
  assert.Equal(t, 0, got)
@@ -71,14 +67,26 @@ func TestAvroGen_RequiredFlags(t *testing.T) {
  }
 }
 
+func TestAvroGen_GeneratesSchemaStdout(t *testing.T) {
+ var buf bytes.Buffer
+
+ args := []string{"avrogen", "-pkg", "testpkg", "testdata/schema.avsc"}
+ gotCode := realMain(args, io.Discard, &buf)
+ require.Equal(t, 0, gotCode)
+
+ want, err := os.ReadFile("testdata/golden.go")
+ require.NoError(t, err)
+ assert.Equal(t, want, buf.Bytes())
+}
+
 func TestAvroGen_GeneratesSchema(t *testing.T) {
  path, err := os.MkdirTemp("./", "avrogen")
  require.NoError(t, err)
  t.Cleanup(func() { _ = os.RemoveAll(path) })
 
  file := filepath.Join(path, "test.go")
  args := []string{"avrogen", "-pkg", "testpkg", "-o", file, "testdata/schema.avsc"}
- gotCode := realMain(args, io.Discard)
+ gotCode := realMain(args, io.Discard, io.Discard)
  require.Equal(t, 0, gotCode)
 
  got, err := os.ReadFile(file)
@@ -101,7 +109,7 @@ func TestAvroGen_GeneratesSchemaWithFullname(t *testing.T) {
 
  file := filepath.Join(path, "test.go")
  args := []string{"avrogen", "-pkg", "testpkg", "-o", file, "-fullname", "testdata/schema.avsc"}
- gotCode := realMain(args, io.Discard)
+ gotCode := realMain(args, io.Discard, io.Discard)
  require.Equal(t, 0, gotCode)
 
  got, err := os.ReadFile(file)
@@ -124,7 +132,7 @@ func TestAvroGen_GeneratesSchemaWithEncoders(t *testing.T) {
 
  file := filepath.Join(path, "test.go")
  args := []string{"avrogen", "-pkg", "testpkg", "-o", file, "-encoders", "testdata/schema.avsc"}
- gotCode := realMain(args, io.Discard)
+ gotCode := realMain(args, io.Discard, io.Discard)
  require.Equal(t, 0, gotCode)
 
  got, err := os.ReadFile(file)