Include dotfiles in error message file listings (#1728)

The error messages shown when buildpack detection fails
(or when detection passes, but no required package manager
files are found later) include a file listing of the project to help
with debugging. (e.g. to make misspellings or having forgotten
to commit files more obvious.)

Previously these file listings didn't include dotfiles, which
meant not all project files would be shown. This is particularly
relevant given that the the newly supported `.python-version`
file is a dotfile.

GUS-W-17524155.

Author: edmorley

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## [Unreleased]
 
+- Improved the file listing in the error messages shown when buildpack detection fails or when no Python package manager files are found. ([#1728](https://github.com/heroku/heroku-buildpack-python/pull/1728))
 
 ## [v272] - 2024-12-13
 

bin/detect

@@ -55,7 +55,7 @@ directory of its source code.
 
 Currently the root directory of your app contains:
 
-$(ls -1 --indicator-style=slash "${BUILD_DIR}" || true)
+$(ls -1A --indicator-style=slash "${BUILD_DIR}" || true)
 
 If your app already has a package manager file, check that it:
 

lib/package_manager.sh

@@ -80,7 +80,7 @@ function package_manager::determine_package_manager() {
 
 				Currently the root directory of your app contains:
 
-				$(ls -1 --indicator-style=slash "${build_dir}" || true)
+				$(ls -1A --indicator-style=slash "${build_dir}" || true)
 
 				If your app already has a package manager file, check that it:
 

spec/fixtures/no_python_project_files/.example-dotfile

@@ -23,6 +23,7 @@
           remote:  !     
           remote:  !     Currently the root directory of your app contains:
           remote:  !     
+          remote:  !     .example-dotfile
           remote:  !     README.md
           remote:  !     subdir/
           remote:  !     

spec/fixtures/pyproject_toml_only/.example-dotfile

@@ -19,6 +19,7 @@
           remote:  !     
           remote:  !     Currently the root directory of your app contains:
           remote:  !     
+          remote:  !     .example-dotfile
           remote:  !     pyproject.toml
           remote:  !     subdir/
           remote:  !