builder: add acctests for image_architecture

The image_architecture attribute when introduced caused problems with
some existing configs, so to avoid introducing further bugs in the
future, we add new accetpance tests that ensure the default value is
maintained, and that the architecture is forwarded to the final image
being created.

builder/googlecompute/builder_acc_test.go

@@ -14,7 +14,9 @@ import (
 	"os/exec"
 	"strings"
 	"testing"
+	"time"
 
+	"github.com/hashicorp/packer-plugin-googlecompute/lib/common"
 	"github.com/hashicorp/packer-plugin-sdk/acctest"
 )
 
@@ -284,3 +286,101 @@ func TestAccBuilder_WithMultipleDisks(t *testing.T) {
 	}
 	acctest.TestPlugin(t, testCase)
 }
+
+func TestAccBuilder_ImageArchVariations(t *testing.T) {
+	tests := []struct {
+		name            string
+		baseImageFamily string
+		arch            string
+		instanceType    string
+		expectedArch    string
+	}{
+		{
+			name:            "googlecompute-packer-with-x86-64-explicit-image-arch",
+			baseImageFamily: "fedora-cloud-38",
+			arch:            "x86_64",
+			instanceType:    "e2-standard-2",
+			expectedArch:    "x86_64",
+		},
+		{
+			name:            "googlecompute-packer-with-x86-64-implicit-image-arch",
+			baseImageFamily: "fedora-cloud-38",
+			arch:            "",
+			instanceType:    "e2-standard-2",
+			// Empty for this case as the source image has an empty
+			// architecture, so this gets forwarded as-is
+			expectedArch: "",
+		},
+		{
+			name:            "googlecompute-packer-with-arm64-explicit-image-arch",
+			baseImageFamily: "ubuntu-minimal-2204-lts-arm64",
+			arch:            "arm64",
+			instanceType:    "t2a-standard-2",
+			expectedArch:    "arm64",
+		},
+		{
+			name:            "googlecompute-packer-with-arm64-implicit-image-arch",
+			baseImageFamily: "ubuntu-minimal-2204-lts-arm64",
+			arch:            "",
+			instanceType:    "t2a-standard-2",
+			expectedArch:    "arm64",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			imageName := fmt.Sprintf("%s-%d", tt.name, time.Now().UTC().Unix())
+
+			tmpl, err := testDataFs.ReadFile("testdata/image_arch_builds.pkr.hcl")
+			if err != nil {
+				t.Fatalf("failed to read testdata file: %s", err)
+			}
+
+			rawTemplate := fmt.Sprintf(string(tmpl), imageName, tt.baseImageFamily, tt.arch, tt.instanceType)
+
+			testCase := &acctest.PluginTestCase{
+				Name:     tt.name,
+				Template: rawTemplate,
+				Teardown: func() error {
+					driver, err := common.NewDriverGCE(common.GCEDriverConfig{})
+					if err != nil {
+						return fmt.Errorf("failed to create GCE driver: %s", err)
+					}
+
+					chErr := driver.DeleteImage(os.Getenv("GOOGLE_PROJECT_ID"), imageName)
+					for err := range chErr {
+						return err
+					}
+					return nil
+				},
+				Check: func(buildCommand *exec.Cmd, logfile string) error {
+					if buildCommand.ProcessState != nil {
+						if buildCommand.ProcessState.ExitCode() != 0 {
+							return fmt.Errorf("Bad exit code. Logfile: %s", logfile)
+						}
+					}
+
+					driver, err := common.NewDriverGCE(common.GCEDriverConfig{})
+					if err != nil {
+						return fmt.Errorf("failed to create GCE driver: %s", err)
+					}
+
+					img, err := driver.GetImageFromProject(os.Getenv("GOOGLE_PROJECT_ID"), imageName, false)
+					if err != nil {
+						return fmt.Errorf("failed to get image: %s", err)
+					}
+
+					// Manually uppercase the arch as it cannot be used
+					// for the image name otherwise
+					upperArch := strings.ToUpper(tt.expectedArch)
+					if img.Architecture != upperArch {
+						return fmt.Errorf("image architecture mismatch, expected %q, got %q", upperArch, img.Architecture)
+					}
+
+					return nil
+				},
+			}
+			acctest.TestPlugin(t, testCase)
+		})
+	}
+}

builder/googlecompute/testdata/image_arch_builds.pkr.hcl

@@ -0,0 +1,23 @@
+# Copyright (c) HashiCorp, Inc.
+# SPDX-License-Identifier: MPL-2.0
+
+variable "project" {
+  type    = string
+  default = "${env("GOOGLE_PROJECT_ID")}"
+}
+
+locals { timestamp = regex_replace(timestamp(), "[- TZ:]", "") }
+
+source "googlecompute" "autogenerated_1" {
+  image_name          = "%s"
+  project_id          = "${var.project}"
+  source_image_family = "%s"
+  ssh_username        = "packer"
+  zone                = "us-central1-a"
+  image_architecture  = "%s"
+  machine_type        = "%s"
+}
+
+build {
+  sources = ["source.googlecompute.autogenerated_1"]
+}