fix: gh gist edit panic when no file in a gist (cli#10627)

* fix: `gh gist edit` panic when no file in a gist

* fix: improve error message

Signed-off-by: Babak K. Shandiz <babakks@github.com>

---------

Signed-off-by: Babak K. Shandiz <babakks@github.com>
Co-authored-by: Babak K. Shandiz <babakks@github.com>

Author: phanen

pkg/cmd/gist/edit/edit.go

@@ -236,6 +236,8 @@ func editRun(opts *EditOptions) error {
 		if filename == "" {
 			if len(candidates) == 1 {
 				filename = candidates[0]
+			} else if len(candidates) == 0 {
+				return errors.New("no file in the gist")
 			} else {
 				if !opts.IO.CanPrompt() {
 					return errors.New("unsure what file to edit; either specify --filename or run interactively")

pkg/cmd/gist/edit/edit_test.go

@@ -557,6 +557,30 @@ func Test_editRun(t *testing.T) {
 			},
 			wantErr: "gist ID or URL required when not running interactively",
 		},
+		{
+			name: "edit no-file gist (#10626)",
+			opts: &EditOptions{
+				Selector: "1234",
+			},
+			mockGist: &shared.Gist{
+				ID:    "1234",
+				Files: map[string]*shared.GistFile{},
+				Owner: &shared.GistOwner{Login: "octocat"},
+			},
+			wantErr: "no file in the gist",
+		},
+		{
+			name: "edit no-file gist, nil map (#10626)",
+			opts: &EditOptions{
+				Selector: "1234",
+			},
+			mockGist: &shared.Gist{
+				ID:    "1234",
+				Files: nil,
+				Owner: &shared.GistOwner{Login: "octocat"},
+			},
+			wantErr: "no file in the gist",
+		},
 	}
 
 	for _, tt := range tests {

pkg/cmd/gist/shared/shared.go

@@ -44,6 +44,9 @@ func (g Gist) Filename() string {
 	for fn := range g.Files {
 		filenames = append(filenames, fn)
 	}
+	if len(filenames) == 0 {
+		return ""
+	}
 	sort.Strings(filenames)
 	return filenames[0]
 }

pkg/cmd/gist/shared/shared_test.go

@@ -163,6 +163,33 @@ func TestPromptGists(t *testing.T) {
 			response: `{ "data": { "viewer": { "gists": { "nodes": [] } } } }`,
 			wantOut:  Gist{},
 		},
+		{
+			name: "prompt list contains no-file gist (#10626)",
+			prompterStubs: func(pm *prompter.MockPrompter) {
+				pm.RegisterSelect("Select a gist",
+					[]string{"  about 6 hours ago", "gistfile0.txt  about 6 hours ago"},
+					func(_, _ string, opts []string) (int, error) {
+						return prompter.IndexFor(opts, "  about 6 hours ago")
+					})
+			},
+			response: `{ "data": { "viewer": { "gists": { "nodes": [
+							{
+								"name": "1234",
+								"files": [],
+								"description": "",
+								"updatedAt": "%[1]v",
+								"isPublic": true
+							},
+							{
+								"name": "5678",
+								"files": [{ "name": "gistfile0.txt" }],
+								"description": "",
+								"updatedAt": "%[1]v",
+								"isPublic": true
+							}
+						] } } } }`,
+			wantOut: Gist{ID: "1234", Files: map[string]*GistFile{}, UpdatedAt: sixHoursAgo, Public: true},
+		},
 	}
 
 	ios, _, _, _ := iostreams.Test()