add cmdlxcconfig tests

internal/cmdlxcconfig/BUILD

@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 go_library(
     name = "go_default_library",
@@ -11,3 +11,14 @@ go_library(
         "@org_uber_go_multierr//:go_default_library",
     ],
 )
+
+go_test(
+    name = "go_default_test",
+    srcs = ["cmdlxcconfig_test.go"],
+    embed = [":go_default_library"],
+    deps = [
+        "@com_github_jessevdk_go_flags//:go_default_library",
+        "@com_github_stretchr_testify//assert:go_default_library",
+        "@com_github_stretchr_testify//require:go_default_library",
+    ],
+)

internal/cmdlxcconfig/cmdlxcconfig.go

@@ -11,9 +11,12 @@ import (
 	"go.uber.org/multierr"
 )
 
-// Command is "lxcconfig" command
+const _description = "Create an LXC-compatible container configuration"
+
 type (
+	// Command is an implementation of go-flags.Command
 	Command struct {
+		configer func(io.ReadSeeker, io.Writer) error
 		Stdout   io.Writer
 
 		PositionalArgs struct {
@@ -25,12 +28,13 @@ type (
 
 func NewCommand() *Command {
 	return &Command{
+		configer: lxcconfig.LXCConfig,
 		Stdout:   os.Stdout,
 	}
 }
 
-func (*Command) ShortDesc() string { return "Create an LXC-compatible container configuration" }
-func (*Command) LongDesc() string  { return "" }
+func (*Command) ShortDesc() string { return _description }
+func (*Command) LongDesc() string  { return _description }
 
 // Execute executes lxcconfig Command
 func (c *Command) Execute(args []string) (err error) {
@@ -57,5 +61,5 @@ func (c *Command) Execute(args []string) (err error) {
 		out = outf
 	}
 
-	return lxcconfig.LXCConfig(rd, out)
+	return c.configer(rd, out)
 }

internal/cmdlxcconfig/cmdlxcconfig_test.go

@@ -0,0 +1,93 @@
+package cmdlxcconfig
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"path/filepath"
+	"testing"
+
+	goflags "github.com/jessevdk/go-flags"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestExecute(t *testing.T) {
+	var _foo = []byte("foo foo")
+
+	tests := []struct {
+		name    string
+		fixture func(*testing.T, string)
+		infile  string
+		outfile string
+		wantErr string
+	}{
+		{
+			name:   "ok passthrough via stdout",
+			infile: "t10-in.txt",
+			fixture: func(t *testing.T, dir string) {
+				fname := filepath.Join(dir, "t10-in.txt")
+				require.NoError(t, ioutil.WriteFile(fname, _foo, 0644))
+			},
+			outfile: "-",
+		},
+		{
+			name:   "ok passthrough via file",
+			infile: "t20-in.txt",
+			fixture: func(t *testing.T, dir string) {
+				fname := filepath.Join(dir, "t20-in.txt")
+				require.NoError(t, ioutil.WriteFile(fname, _foo, 0644))
+			},
+			outfile: "t20-out.txt",
+		},
+		{
+			name:    "infile does not exist",
+			infile:  "t3-does-not-exist.txt",
+			wantErr: "^open .*t3-does-not-exist.txt: no such file or directory$",
+		},
+		{
+			name:    "outpath dir not writable",
+			outfile: filepath.Join("t4", "does", "not", "exist"),
+			wantErr: "^create: open .*/t4/does/not/exist: no such file or directory",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			dir := t.TempDir()
+			var stdout bytes.Buffer
+			c := &Command{Stdout: &stdout}
+			if tt.fixture != nil {
+				tt.fixture(t, dir)
+			}
+			if tt.outfile != "-" {
+				tt.outfile = filepath.Join(dir, tt.outfile)
+			}
+			inf := filepath.Join(dir, tt.infile)
+			c.PositionalArgs.Infile = goflags.Filename(inf)
+			c.PositionalArgs.Outfile = tt.outfile
+			c.configer = configerPassthrough
+
+			err := c.Execute(nil)
+			if tt.wantErr != "" {
+				require.Error(t, err)
+				assert.Regexp(t, tt.wantErr, err.Error())
+				return
+			}
+			var out []byte
+			require.NoError(t, err)
+			if tt.outfile == "-" {
+				out = stdout.Bytes()
+			} else {
+				out, err = ioutil.ReadFile(tt.outfile)
+				require.NoError(t, err)
+			}
+			assert.Equal(t, []byte("foo foo"), out)
+		})
+	}
+}
+
+func configerPassthrough(r io.ReadSeeker, w io.Writer) error {
+	_, err := io.Copy(w, r)
+	return err
+}

internal/cmdrootfs/cmdrootfs.go

@@ -11,7 +11,10 @@ import (
 	"go.uber.org/multierr"
 )
 
+const _description = "Flatten a docker container image to a tarball"
+
 type (
+	// Command is an implementation of go-flags.Command
 	Command struct {
 		flattener func(io.ReadSeeker, io.Writer) error
 		Stdout    io.Writer
@@ -30,8 +33,8 @@ func NewCommand() *Command {
 	}
 }
 
-func (*Command) ShortDesc() string { return "Flatten a docker container image to a tarball" }
-func (*Command) LongDesc() string  { return "" }
+func (*Command) ShortDesc() string { return _description }
+func (*Command) LongDesc() string  { return _description }
 
 // Execute executes rootfs Command
 func (c *Command) Execute(args []string) (err error) {