osbuild/osbuild-exec: make osbuild command a variable

This is useful for testing, as osbuild can be overwritten in unit tests.

Author: croissanne

pkg/osbuild/osbuild-exec.go

@@ -24,6 +24,8 @@ const (
 	MonitorLog     = "LogMonitor"
 )
 
+var OSBuildCmd = "osbuild"
+
 type OSBuildOptions struct {
 	StoreDir  string
 	OutputDir string
@@ -47,7 +49,7 @@ func NewOSBuildCmd(manifest []byte, exports, checkpoints []string, optsPtr *OSBu
 
 	// nolint: gosec
 	cmd := exec.Command(
-		"osbuild",
+		OSBuildCmd,
 		"--store", opts.StoreDir,
 		"--output-directory", opts.OutputDir,
 		fmt.Sprintf("--cache-max-size=%v", cacheMaxSize),
@@ -82,14 +84,16 @@ func NewOSBuildCmd(manifest []byte, exports, checkpoints []string, optsPtr *OSBu
 // Note that osbuild returns non-zero when the pipeline fails. This function
 // does not return an error in this case. Instead, the failure is communicated
 // with its corresponding logs through osbuild.Result.
-func RunOSBuild(manifest []byte, exports, checkpoints []string, errorWriter io.Writer, opts *OSBuildOptions) (*Result, error) {
+func RunOSBuild(manifest []byte, exports, checkpoints []string, errorWriter io.Writer, optsPtr *OSBuildOptions) (*Result, error) {
+	opts := common.ValueOrEmpty(optsPtr)
+
 	if err := CheckMinimumOSBuildVersion(); err != nil {
 		return nil, err
 	}
 
 	var stdoutBuffer bytes.Buffer
 	var res Result
-	cmd := NewOSBuildCmd(manifest, exports, checkpoints, opts)
+	cmd := NewOSBuildCmd(manifest, exports, checkpoints, &opts)
 
 	if opts.JSONOutput {
 		cmd.Stdout = &stdoutBuffer
@@ -152,7 +156,7 @@ func CheckMinimumOSBuildVersion() error {
 // OSBuildVersion returns the version of osbuild.
 func OSBuildVersion() (string, error) {
 	var stdoutBuffer bytes.Buffer
-	cmd := exec.Command("osbuild", "--version")
+	cmd := exec.Command(OSBuildCmd, "--version")
 	cmd.Stdout = &stdoutBuffer
 
 	err := cmd.Run()
@@ -169,7 +173,7 @@ func OSBuildVersion() (string, error) {
 
 // OSBuildInspect converts a manifest to an inspected manifest.
 func OSBuildInspect(manifest []byte) ([]byte, error) {
-	cmd := exec.Command("osbuild", "--inspect")
+	cmd := exec.Command(OSBuildCmd, "--inspect")
 	cmd.Stdin = bytes.NewBuffer(manifest)
 
 	out, err := cmd.Output()

pkg/osbuild/osbuild-exec_test.go

@@ -3,6 +3,8 @@ package osbuild_test
 import (
 	"fmt"
 	"io"
+	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -11,6 +13,21 @@ import (
 	"github.com/osbuild/images/pkg/osbuild"
 )
 
+func mockOsbuildCmd(s string) (restore func()) {
+	saved := osbuild.OSBuildCmd
+	osbuild.OSBuildCmd = s
+	return func() {
+		osbuild.OSBuildCmd = saved
+	}
+}
+
+func makeFakeOsbuild(t *testing.T, content string) string {
+	p := filepath.Join(t.TempDir(), "fake-osbuild")
+	err := os.WriteFile(p, []byte("#!/bin/sh\n"+content), 0755)
+	assert.NoError(t, err)
+	return p
+}
+
 func TestNewOSBuildCmdNilOptions(t *testing.T) {
 	mf := []byte(`{"real": "manifest"}`)
 	cmd := osbuild.NewOSBuildCmd(mf, nil, nil, nil)
@@ -91,3 +108,23 @@ func TestNewOSBuildCmdFullOptions(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, mf, stdin)
 }
+
+func TestRunOSBuild(t *testing.T) {
+	fakeOsbuildBinary := makeFakeOsbuild(t, `
+if [ "$1" = "--version" ]; then
+    echo '90000.0'
+else
+    echo '{"success": true}'
+fi
+`)
+	restore := mockOsbuildCmd(fakeOsbuildBinary)
+	defer restore()
+
+	opts := &osbuild.OSBuildOptions{
+		JSONOutput: true,
+	}
+	result, err := osbuild.RunOSBuild([]byte(`{"fake":"manifest"}`), nil, nil, nil, opts)
+	assert.NoError(t, err)
+	assert.NotNil(t, result)
+	assert.True(t, result.Success)
+}