Add end-to-end tests for json subcommand

cmd/json.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"io"
 
 	"github.com/sourcegraph/sourcegraph/lib/errors"
 	"github.com/urfave/cli/v2"
@@ -32,14 +33,14 @@ func jsonCommand() cli.Command {
 			if jsonFlags.from == "" {
 				return errors.New("missing argument for path to SCIP index")
 			}
-			return jsonMain(jsonFlags)
+			return jsonMain(jsonFlags, c.App.Writer)
 		},
 	}
 
 	return json
 }
 
-func jsonMain(flags jsonFlags) error {
+func jsonMain(flags jsonFlags, out io.Writer) error {
 
 	fmt.Println(flags)
 
@@ -53,7 +54,7 @@ func jsonMain(flags jsonFlags) error {
 	}
 
 	jsonBytes, _ := options.Marshal(scipIndex)
-	fmt.Println(string(jsonBytes))
+	out.Write(jsonBytes)
 
 	return nil
 }

cmd/json_test.go

@@ -0,0 +1,69 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"testing"
+
+	"github.com/sourcegraph/scip/bindings/go/scip"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/protobuf/proto"
+)
+
+func TestJSONCommand(t *testing.T) {
+	app := scipApp()
+	// Redirect CLI writer to a buffer
+	var buff bytes.Buffer
+	app.Writer = io.Writer(&buff)
+	idx := makeIndex([]string{"a"}, stringMap{"f": {"b"}}, stringMap{"f": {"a", "b"}})
+
+	idx.Metadata = &scip.Metadata{ProjectRoot: "howdy"}
+
+	// Serialise SCIP index
+	indexBytes, err := proto.Marshal(idx)
+
+	// Write SCIP index to a temp file
+	dir := os.TempDir()
+	file, err := ioutil.TempFile(dir, "scip-cli-json-test*.scip")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.Remove(file.Name())
+
+	_, fErr := file.Write(indexBytes)
+	if fErr != nil {
+		log.Fatal(fErr)
+	}
+
+	// Run the JSON command with the temporary file
+	runErr := app.Run([]string{"scip", "json", "--from", file.Name()})
+	if runErr != nil {
+		log.Fatal(runErr)
+	}
+
+	type JsonIndex struct {
+		Metadata struct {
+			ProjectRoot string `json:"projectRoot"`
+		}
+		Documents []struct {
+			RelativePath string `json:"relativePath"`
+		} `json:"documents"`
+	}
+
+	var roundtripResult JsonIndex
+
+	bytes := buff.Bytes()
+
+	jsonErr := json.Unmarshal(bytes, &roundtripResult)
+	if jsonErr != nil {
+		log.Fatal(jsonErr)
+	}
+
+	require.Equal(t, roundtripResult.Metadata.ProjectRoot, "howdy")
+	require.Equal(t, len(roundtripResult.Documents), 1)
+	require.Equal(t, roundtripResult.Documents[0].RelativePath, "f")
+}