Fix race condition and tests

git/operations.go

@@ -10,6 +10,7 @@ import (
 	"os"
 	"os/exec"
 	"strings"
+	"sync"
 
 	"github.com/pkg/errors"
 )
@@ -327,6 +328,23 @@ func traceGitCommand(args []string, config gitCmdConfig, stdOutAndStdErr string)
 	)
 }
 
+type threadSafeBuffer struct {
+	bytes.Buffer
+	sync.Mutex
+}
+
+func (b *threadSafeBuffer) Write(p []byte) (n int, err error) {
+	b.Lock()
+	defer b.Unlock()
+	return b.Buffer.Write(p)
+}
+
+func (b *threadSafeBuffer) ReadFrom(r io.Reader) (n int64, err error) {
+	b.Lock()
+	defer b.Unlock()
+	return b.Buffer.ReadFrom(r)
+}
+
 // execGitCmd runs a `git` command with the supplied arguments.
 func execGitCmd(ctx context.Context, args []string, config gitCmdConfig) error {
 	c := exec.CommandContext(ctx, "git", args...)
@@ -335,8 +353,7 @@ func execGitCmd(ctx context.Context, args []string, config gitCmdConfig) error {
 		c.Dir = config.dir
 	}
 	c.Env = append(env(), config.env...)
-
-	stdOutAndStdErr := &bytes.Buffer{}
+	stdOutAndStdErr := &threadSafeBuffer{}
 	c.Stdout = stdOutAndStdErr
 	c.Stderr = stdOutAndStdErr
 	if config.out != nil {

git/operations_test.go

@@ -316,7 +316,7 @@ func TestTraceGitCommand(t *testing.T) {
 					dir: "/tmp/flux-working628880789",
 				},
 			},
-			expected: `TRACE: command="git clone --branch master /tmp/flux-gitclone239583443 /tmp/flux-working628880789" out="" err="" dir="/tmp/flux-working628880789" env=""`,
+			expected: `TRACE: command="git clone --branch master /tmp/flux-gitclone239583443 /tmp/flux-working628880789" out="" dir="/tmp/flux-working628880789" env=""`,
 		},
 		{
 			name: "git rev-list",
@@ -333,7 +333,7 @@ func TestTraceGitCommand(t *testing.T) {
 					dir: "/tmp/flux-gitclone239583443",
 				},
 			},
-			expected: `TRACE: command="git rev-list --max-count 1 flux-sync --" out="b9d6a543acf8085ff6bed23fac17f8dc71bfcb66" err="" dir="/tmp/flux-gitclone239583443" env=""`,
+			expected: `TRACE: command="git rev-list --max-count 1 flux-sync --" out="b9d6a543acf8085ff6bed23fac17f8dc71bfcb66" dir="/tmp/flux-gitclone239583443" env=""`,
 		},
 		{
 			name: "git config email",
@@ -347,7 +347,7 @@ func TestTraceGitCommand(t *testing.T) {
 					dir: "/tmp/flux-working056923691",
 				},
 			},
-			expected: `TRACE: command="git config user.email [email protected]" out="" err="" dir="/tmp/flux-working056923691" env=""`,
+			expected: `TRACE: command="git config user.email [email protected]" out="" dir="/tmp/flux-working056923691" env=""`,
 		},
 		{
 			name: "git notes",
@@ -363,15 +363,14 @@ func TestTraceGitCommand(t *testing.T) {
 				},
 				out: "refs/notes/flux",
 			},
-			expected: `TRACE: command="git notes --ref flux get-ref" out="refs/notes/flux" err="" dir="/tmp/flux-working647148942" env=""`,
+			expected: `TRACE: command="git notes --ref flux get-ref" out="refs/notes/flux" dir="/tmp/flux-working647148942" env=""`,
 		},
 	}
 	for _, example := range examples {
 		actual := traceGitCommand(
 			example.input.args,
 			example.input.config,
 			example.input.out,
-			example.input.err,
 		)
 		assert.Equal(t, example.expected, actual)
 	}