cmd/cue/cmd: add get to define CUE package from Go

Update #24

Change-Id: Ief47b7295249354d5eafbe0bcf33ea26dd6dfdc7
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/1723
Reviewed-by: Marcel van Lohuizen <[email protected]>

cmd/cue/cmd/common_test.go

@@ -42,8 +42,8 @@ func runCommand(t *testing.T, f func(cmd *cobra.Command, args []string) error, n
 	if err != nil {
 		log.Fatal(err)
 	}
-
 	const dir = "./testdata"
+
 	filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
 		t.Run(path, func(t *testing.T) {
 			if err != nil {

cmd/cue/cmd/get.go

@@ -0,0 +1,45 @@
+// Copyright 2018 The CUE 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 cmd
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+// getCmd represents the extract command
+var getCmd = &cobra.Command{
+	Use:   "get <language> [packages]",
+	Short: "add dependencies to the current module",
+	Long: `Get downloads packages or modules for CUE or another language
+to include them in the module's pkg directory.
+
+Get requires an additional language field to determine for which
+language definitions should be fetched. If get fetches definitions
+for a language other than CUE, the definitions are extracted from
+the source of the respective language and stored.
+The specifics on how dependencies are fechted and converted vary
+per language and are documented in the respective subcommands.
+`,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		fmt.Println("get must be run as one of its subcommands")
+		return nil
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(getCmd)
+}