Add unit test for findRunImage

pkg/skaffold/build/buildpacks/lifecycle.go

@@ -65,7 +65,7 @@ func (b *Builder) build(ctx context.Context, out io.Writer, a *latest.Artifact,
 		// If ForcePull is true: we will let `pack` always pull.
 		// Ideally, we add a `--pullIfNotPresent` option to upstream `pack`.
 		var err error
-		runImage, err = b.findRunImage(ctx, artifact, builderImage)
+		runImage, err = b.findRunImage(ctx, artifact)
 		if err != nil {
 			return "", err
 		}

pkg/skaffold/build/buildpacks/metadata.go

@@ -20,6 +20,8 @@ import (
 	"context"
 	"encoding/json"
 
+	"github.com/pkg/errors"
+
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema/latest"
 )
 
@@ -36,20 +38,20 @@ type metadata struct {
 }
 
 // TODO(dgageot): mirrors
-func (b *Builder) findRunImage(ctx context.Context, a *latest.BuildpackArtifact, builder string) (string, error) {
+func (b *Builder) findRunImage(ctx context.Context, a *latest.BuildpackArtifact) (string, error) {
 	if a.RunImage != "" {
 		return a.RunImage, nil
 	}
 
-	cfg, err := b.localDocker.ConfigFile(ctx, builder)
+	cfg, err := b.localDocker.ConfigFile(ctx, a.Builder)
 	if err != nil {
-		return "", err
+		return "", errors.Wrapf(err, "unable to find image %q", a.Builder)
 	}
 
 	var m metadata
 	label := cfg.Config.Labels["io.buildpacks.builder.metadata"]
 	if err := json.Unmarshal([]byte(label), &m); err != nil {
-		return "", err
+		return "", errors.Wrapf(err, "unable to decode image labels for %q", a.Builder)
 	}
 
 	return m.Stack.RunImage.Image, nil

pkg/skaffold/build/buildpacks/metadata_test.go

@@ -0,0 +1,112 @@
+/*
+Copyright 2019 The Skaffold Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package buildpacks
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+
+	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/docker"
+	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema/latest"
+	"github.com/GoogleContainerTools/skaffold/testutil"
+)
+
+type fakeDocker struct {
+	docker.LocalDaemon
+
+	configFiles map[string]*v1.ConfigFile
+}
+
+func (f *fakeDocker) ConfigFile(ctx context.Context, image string) (*v1.ConfigFile, error) {
+	if configFile, present := f.configFiles[image]; present {
+		return configFile, nil
+	}
+	return nil, errors.New("Not found")
+}
+
+func TestFindRunImage(t *testing.T) {
+	tests := []struct {
+		description      string
+		artifact         *latest.BuildpackArtifact
+		expectedRunImage string
+		expectedError    string
+	}{
+		{
+			description: "user specified run image",
+			artifact: &latest.BuildpackArtifact{
+				RunImage: "custom-image/run",
+			},
+			expectedRunImage: "custom-image/run",
+		},
+		{
+			description: "default run image",
+			artifact: &latest.BuildpackArtifact{
+				Builder: "image/build",
+			},
+			expectedRunImage: "image/run",
+		},
+		{
+			description: "unable to find image",
+			artifact: &latest.BuildpackArtifact{
+				Builder: "unknown",
+			},
+			expectedError: `unable to find image "unknown"`,
+		},
+		{
+			description: "invalid-labels",
+			artifact: &latest.BuildpackArtifact{
+				Builder: "invalid-labels",
+			},
+			expectedError: `unable to decode image labels for "invalid-labels"`,
+		},
+	}
+	for _, test := range tests {
+		testutil.Run(t, test.description, func(t *testutil.T) {
+			localDocker := &fakeDocker{
+				configFiles: map[string]*v1.ConfigFile{
+					"image/build": {
+						Config: v1.Config{
+							Labels: map[string]string{
+								"io.buildpacks.builder.metadata": `{"stack":{"runImage":{"image": "image/run"}}}`,
+							},
+						},
+					},
+					"invalid-labels": {
+						Config: v1.Config{
+							Labels: map[string]string{
+								"io.buildpacks.builder.metadata": "invalid",
+							},
+						},
+					},
+				},
+			}
+
+			builder := NewArtifactBuilder(localDocker, false)
+			runImage, err := builder.findRunImage(context.Background(), test.artifact)
+
+			if test.expectedError == "" {
+				t.CheckNoError(err)
+				t.CheckDeepEqual(test.expectedRunImage, runImage)
+			} else {
+				t.CheckErrorContains(test.expectedError, err)
+			}
+		})
+	}
+}