Attempt to fix output test flakes

code-asher · code-asher · commit cfd4e72589fe · 2022-09-26T16:09:12.000-05:00
In TestStderrVsStdout maybe process.Wait() yielded before the copy got
the last bit of stdout?  I am not sure that is possible but add a wait
group.

In the testExecer case there was already a wait group but I replaced it
to be consistent.  There is a flake here as well but I have no idea how
to fix it.
diff --git a/client_test.go b/client_test.go
@@ -15,6 +15,7 @@ import (
 	"cdr.dev/slog/sloggers/slogtest/assert"
 	"cdr.dev/wsep/internal/proto"
 	"github.com/google/go-cmp/cmp"
+	"golang.org/x/sync/errgroup"
 	"nhooyr.io/websocket"
 )
 
@@ -151,12 +152,22 @@ func TestStderrVsStdout(t *testing.T) {
 	})
 	assert.Success(t, "start command", err)
 
-	go io.Copy(&stdout, process.Stdout())
-	go io.Copy(&stderr, process.Stderr())
+	var outputgroup errgroup.Group
+	outputgroup.Go(func() error {
+		_, err := io.Copy(&stdout, process.Stdout())
+		return err
+	})
+	outputgroup.Go(func() error {
+		_, err := io.Copy(&stderr, process.Stderr())
+		return err
+	})
 
 	err = process.Wait()
 	assert.Success(t, "wait for process to complete", err)
 
+	err = outputgroup.Wait()
+	assert.Success(t, "wait for output", err)
+
 	assert.Equal(t, "stdout", "stdout-message", strings.TrimSpace(stdout.String()))
 	assert.Equal(t, "stderr", "stderr-message", strings.TrimSpace(stderr.String()))
 }
diff --git a/localexec_test.go b/localexec_test.go
@@ -4,14 +4,13 @@ import (
 	"bytes"
 	"context"
 	"io"
-	"io/ioutil"
 	"os"
 	"strings"
-	"sync"
 	"testing"
 	"time"
 
 	"cdr.dev/slog/sloggers/slogtest/assert"
+	"golang.org/x/sync/errgroup"
 )
 
 func TestLocalExec(t *testing.T) {
@@ -27,35 +26,33 @@ func testExecer(ctx context.Context, t *testing.T, execer Execer) {
 		Command: "pwd",
 	})
 	assert.Success(t, "start local cmd", err)
+
 	var (
-		stderr = process.Stderr()
-		stdout = process.Stdout()
-		wg     sync.WaitGroup
+		stdout bytes.Buffer
+		stderr bytes.Buffer
 	)
 
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
+	var outputgroup errgroup.Group
+	outputgroup.Go(func() error {
+		_, err := io.Copy(&stdout, process.Stdout())
+		return err
+	})
+	outputgroup.Go(func() error {
+		_, err := io.Copy(&stderr, process.Stderr())
+		return err
+	})
 
-		stdoutByt, err := ioutil.ReadAll(stdout)
-		assert.Success(t, "read stdout", err)
-		wd, err := os.Getwd()
-		assert.Success(t, "get real working dir", err)
+	err = process.Wait()
+	assert.Success(t, "wait for process to complete", err)
 
-		assert.Equal(t, "stdout", wd, strings.TrimSuffix(string(stdoutByt), "\n"))
-	}()
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
+	err = outputgroup.Wait()
+	assert.Success(t, "wait for output", err)
 
-		stderrByt, err := ioutil.ReadAll(stderr)
-		assert.Success(t, "read stderr", err)
-		assert.True(t, "len stderr", len(stderrByt) == 0)
-	}()
+	wd, err := os.Getwd()
+	assert.Success(t, "get real working dir", err)
 
-	wg.Wait()
-	err = process.Wait()
-	assert.Success(t, "wait for process to complete", err)
+	assert.Equal(t, "stdout", wd, strings.TrimSpace(stdout.String()))
+	assert.Equal(t, "stderr", "", strings.TrimSpace(stderr.String()))
 }
 
 func TestExitCode(t *testing.T) {
