Add test and trailing new line to apko.lock.json files.

- There was no test that `apko lock' command works
- Some code-quality tools like end-of-file-fixer were annoyed thay .apko.lock.files are not ending with a new-line character.

Signed-off-by: Piotr Tabor <piotr.tabor@snowflake.com>

internal/cli/lock.go

@@ -65,7 +65,7 @@ func lockInternal(cmdName string, extension string, deprecated string) *cobra.Co
 
 			archs := types.ParseArchitectures(archstrs)
 
-			return ResolveCmd(
+			return LockCmd(
 				cmd.Context(),
 				output,
 				archs,
@@ -86,7 +86,7 @@ func lockInternal(cmdName string, extension string, deprecated string) *cobra.Co
 	return cmd
 }
 
-func ResolveCmd(ctx context.Context, output string, archs []types.Architecture, opts []build.Option) error {
+func LockCmd(ctx context.Context, output string, archs []types.Architecture, opts []build.Option) error {
 	log := clog.FromContext(ctx)
 	wd, err := os.MkdirTemp("", "apko-*")
 	if err != nil {

internal/cli/lock_test.go

@@ -0,0 +1,56 @@
+// Copyright 2023 Chainguard, Inc.
+//
+// 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 cli_test
+
+import (
+	"bytes"
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/stretchr/testify/require"
+
+	"chainguard.dev/apko/internal/cli"
+	"chainguard.dev/apko/pkg/build"
+	"chainguard.dev/apko/pkg/build/types"
+)
+
+func TestLock(t *testing.T) {
+	ctx := context.Background()
+	tmp := t.TempDir()
+
+	golden := filepath.Join("testdata", "apko.lock.json")
+
+	config := filepath.Join("testdata", "apko.yaml")
+	archs := types.ParseArchitectures([]string{"amd64", "arm64"})
+	opts := []build.Option{build.WithConfig(config)}
+	outputPath := filepath.Join(tmp, "apko.lock.json")
+
+	err := cli.LockCmd(ctx, outputPath, archs, opts)
+	require.NoError(t, err)
+
+	want, err := os.ReadFile(golden)
+	require.NoError(t, err)
+	got, err := os.ReadFile(outputPath)
+	require.NoError(t, err)
+
+	if !bytes.Equal(want, got) {
+		if diff := cmp.Diff(want, got); diff != "" {
+			t.Errorf("Mismatched lock files: (-%q +%q):\n%s", golden, outputPath, diff)
+		}
+	}
+}

internal/cli/testdata/apko.lock.json

@@ -98,4 +98,4 @@
       }
     ]
   }
-}
+}

pkg/lock/lock.go

@@ -62,6 +62,8 @@ func (lock Lock) SaveToFile(lockFile string) error {
 	if err != nil {
 		return fmt.Errorf("failed to marshall json: %w", err)
 	}
-
+	// Github and pre-commit checks (like end-of-file-fixer) are expecting ASCII files
+	// to end with a newline that marshal is not providing.
+	jsonb = append(jsonb, '\n')
 	return os.WriteFile(lockFile, jsonb, os.ModePerm)
 }