refactor(test/fallback): symlink "completions-fallback" on the fly

With the current search order, completions in the test environment
will be used instead of the in-tree completions of `bash-completion`
even for non-fallback completions.  To change the ordering of the
completions, one needs to make symbolic links for all completions in
`test/fallback/completions`. However, with such a setup, all files are
duplicated as hard links in the tarball created by `make dist`
(because Autoconf creates a tarball with the symbolic links fully
resolved to hard links).

Instead, in this patch, we try to set up the symbolic links to
`completions-core` and `completions-fallback` on the startup of the
test suite.

Author: akinomyoga

.pre-commit-config.yaml

@@ -13,7 +13,7 @@ repos:
     hooks:
       - id: shfmt
         types: [text]
-        files: ^(bash_completion(\.d/[^/]+\.bash)?|completions-core/.+|test/(config/bashrc|fixtures/.+/bin/.+|fallback/update-fallback-links|runLint|update-test-cmd-list)|.+\.sh(\.in)?)$
+        files: ^(bash_completion(\.d/[^/]+\.bash)?|completions-core/.+|test/(config/bashrc|fixtures/.+/bin/.+|runLint|update-test-cmd-list)|.+\.sh(\.in)?)$
         exclude: ^completions-core/(\.gitignore|Makefile.*)$
 
   - repo: https://github.com/shellcheck-py/shellcheck-py
@@ -22,7 +22,7 @@ repos:
       - id: shellcheck
         args: [-f, gcc]
         types: [text]
-        files: ^(bash_completion(\.d/[^/]+\.bash)?|completions-core/.+|test/(config/bashrc|fixtures/.+/bin/.+|fallback/update-fallback-links|runLint|update-test-cmd-list)|.+\.sh(\.in)?)$
+        files: ^(bash_completion(\.d/[^/]+\.bash)?|completions-core/.+|test/(config/bashrc|fixtures/.+/bin/.+|runLint|update-test-cmd-list)|.+\.sh(\.in)?)$
         exclude: ^completions-core/(\.gitignore|Makefile.*)$
         require_serial: false  # We disable SC1090 anyway, so parallel is ok
 
@@ -35,13 +35,6 @@ repos:
         files: ^test/t/.+\.py$
         pass_filenames: false
 
-      - id: update-test-fallback-links
-        name: update-test-fallback-links
-        language: script
-        entry: test/fallback/update-fallback-links
-        files: ^completions-fallback/
-        pass_filenames: false
-
   - repo: https://github.com/astral-sh/ruff-pre-commit
     rev: v0.14.3
     hooks:

configure.ac

@@ -41,8 +41,6 @@ doc/Makefile
 helpers/Makefile
 helpers-core/Makefile
 test/Makefile
-test/fallback/Makefile
-test/fallback/completions/Makefile
 test/t/Makefile
 test/t/unit/Makefile
 ])

test/Makefile.am

@@ -1,8 +1,12 @@
-SUBDIRS = fallback t
+SUBDIRS = t
 
-EXTRA_DIST = config \
+EXTRA_DIST = config/bashrc \
+	     config/inputrc \
 	     fixtures \
 	     setup.cfg
 
 CLEANFILES = \
 	fixtures/make/extra_makefile
+
+clean-local:
+	-rm -rf config/bash-completion config/bash-completion-fallback

test/config/bash-completion-fallback/completions

@@ -0,0 +1 @@
+../../../completions-fallback

test/config/bash-completion/completions

@@ -0,0 +1 @@
+../../../completions-core

test/config/bashrc

@@ -1,5 +1,15 @@
 # bashrc file for bash-completion test suite
 
+_comp__test_link()
+{
+    local src=$1 dst=$2
+    if [[ -L $dst || -e $dst ]]; then
+        rm -rf "$dst"
+    fi
+    mkdir -p "${dst%/*}"
+    ln -sf "$src" "$dst"
+}
+
 # Note that we do some initialization that would be too late to do here in
 # conftest.py.
 
@@ -34,9 +44,11 @@ export BASH_COMPLETION_USER_FILE=/dev/null
 # overriding in-tree completions. Setting the user dir would otherwise suffice,
 # but simple xspec completions are only installed if a separate one is not
 # found in *any* completion dirs, and we want to use our "shadow" completion
-# dir with which we cause loading of our in-tree fallback completions
-# instead of possibly (system-)installed upstream ones.
-export BASH_COMPLETION_USER_DIR="$SRCDIRABS/fallback"
+# dir with which we cause loading of our in-tree completions instead of
+# possibly (system-)installed upstream ones.
+_comp__test_link ../../../completions-core "$SRCDIRABS"/config/bash-completion/completions
+_comp__test_link ../../../completions-fallback "$SRCDIRABS"/config/bash-completion-fallback/completions
+export BASH_COMPLETION_USER_DIR="$SRCDIRABS/config/bash-completion:$SRCDIRABS/config/bash-completion-fallback"
 export BASH_COMPLETION_COMPAT_DIR="$SRCDIRABS/../bash_completion.d"
 export XDG_DATA_DIRS=/var/empty