add a test to cmd_ls_integration_test.go: test rest ls --json (#5255)

* cmd_ls: one more test: ls --json to check the JSON lines

validate that the individual JSON lines are valid JSON statements.
Check for snap ID and the path names in the backup.

cmd/restic/cmd_ls_integration_test.go

@@ -1,12 +1,14 @@
 package main
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
 	"strings"
 	"testing"
 
+	"github.com/restic/restic/internal/restic"
 	rtest "github.com/restic/restic/internal/test"
 )
 
@@ -101,3 +103,61 @@ func TestRunLsSort(t *testing.T) {
 		rtest.Equals(t, test.expected, fileList, fmt.Sprintf("mismatch for mode %v", test.mode))
 	}
 }
+
+// JSON lines test
+func TestRunLsJson(t *testing.T) {
+	pathList := []string{
+		"/0",
+		"/0/for_cmd_ls",
+		"/0/for_cmd_ls/file1.txt",
+		"/0/for_cmd_ls/file2.txt",
+		"/0/for_cmd_ls/python.py",
+	}
+
+	env, cleanup := withTestEnvironment(t)
+	defer cleanup()
+
+	testSetupBackupData(t, env)
+	opts := BackupOptions{}
+	testRunBackup(t, env.testdata, []string{"0/for_cmd_ls"}, opts, env.gopts)
+	snapshotIDs := testListSnapshots(t, env.gopts, 1)
+
+	env.gopts.Quiet = true
+	env.gopts.JSON = true
+	buf := testRunLsWithOpts(t, env.gopts, LsOptions{}, []string{"latest"})
+	byteLines := bytes.Split(buf, []byte{'\n'})
+
+	// partial copy of snapshot structure from cmd_ls
+	type lsSnapshot struct {
+		*restic.Snapshot
+		ID          *restic.ID `json:"id"`
+		ShortID     string     `json:"short_id"`     // deprecated
+		MessageType string     `json:"message_type"` // "snapshot"
+		StructType  string     `json:"struct_type"`  // "snapshot", deprecated
+	}
+
+	var snappy lsSnapshot
+	rtest.OK(t, json.Unmarshal(byteLines[0], &snappy))
+	rtest.Equals(t, snappy.ShortID, snapshotIDs[0].Str(), "expected snap IDs to be identical")
+
+	// partial copy of node structure from cmd_ls
+	type lsNode struct {
+		Name        string `json:"name"`
+		Type        string `json:"type"`
+		Path        string `json:"path"`
+		Permissions string `json:"permissions,omitempty"`
+		Inode       uint64 `json:"inode,omitempty"`
+		MessageType string `json:"message_type"` // "node"
+		StructType  string `json:"struct_type"`  // "node", deprecated
+	}
+
+	var testNode lsNode
+	for i, nodeLine := range byteLines[1:] {
+		if len(nodeLine) == 0 {
+			break
+		}
+
+		rtest.OK(t, json.Unmarshal(nodeLine, &testNode))
+		rtest.Equals(t, pathList[i], testNode.Path)
+	}
+}