Use git ls-files to list all file suggestions

pkg/commands/git_commands/working_tree.go

@@ -451,3 +451,19 @@ func (self *WorkingTreeCommands) MergeFileForObjectIDs(strategy string, oursID s
 
 	return self.cmd.New(cmdArgs).RunWithOutput()
 }
+
+// Returns all tracked files in the repo (not in the working tree). The returned entries are
+// relative paths to the repo root, using '/' as the path separator on all platforms.
+// Does not really belong in WorkingTreeCommands, but it's close enough, and we don't seem to have a
+// better place for it right now.
+func (self *WorkingTreeCommands) AllRepoFiles() ([]string, error) {
+	cmdArgs := NewGitCmd("ls-files").Arg("-z").ToArgv()
+	output, err := self.cmd.New(cmdArgs).DontLog().RunWithOutput()
+	if err != nil {
+		return nil, err
+	}
+	if output == "" {
+		return []string{}, nil
+	}
+	return strings.Split(strings.TrimRight(output, "\x00"), "\x00"), nil
+}

pkg/commands/git_commands/working_tree_test.go

@@ -563,3 +563,32 @@ func TestWorkingTreeResetHard(t *testing.T) {
 		})
 	}
 }
+
+func TestWorkingTreeCommands_AllRepoFiles(t *testing.T) {
+	scenarios := []struct {
+		name     string
+		runner   *oscommands.FakeCmdObjRunner
+		expected []string
+	}{
+		{
+			name: "no files",
+			runner: oscommands.NewFakeRunner(t).
+				ExpectGitArgs([]string{"ls-files", "-z"}, "", nil),
+			expected: []string{},
+		},
+		{
+			name: "two files",
+			runner: oscommands.NewFakeRunner(t).
+				ExpectGitArgs([]string{"ls-files", "-z"}, "dir/file1.txt\x00dir2/file2.go\x00", nil),
+			expected: []string{"dir/file1.txt", "dir2/file2.go"},
+		},
+	}
+	for _, s := range scenarios {
+		t.Run(s.name, func(t *testing.T) {
+			instance := buildWorkingTreeCommands(commonDeps{runner: s.runner})
+			result, err := instance.AllRepoFiles()
+			assert.NoError(t, err)
+			assert.Equal(t, s.expected, result)
+		})
+	}
+}