; Reduce quoting for SELECTOR in 'make -C test' (Bug#31744)

Before:

    make -C test SELECTOR='\"foo\"'
    make -C test SELECTOR='(quote (tag :some-tag))'

After:

    make -C test SELECTOR='"foo"'
    make -C test SELECTOR='(tag :some-tag)'

* test/Makefile.in: Use single quotes around the command line call to
ert, this means the user doesn't have to backslash escape double
quotes when writing lisp strings for the selector.  Also wrap the
SELECTOR value in (quote ...) so the user won't have to type it
in (and not get tempted to use the '... reader syntax form which would
now fail to work due to using single quotes around the whole shell
arg).
* test/README: Update instructions accordingly.

2 files changed, 8 insertions, 5 deletions

diff --git a/test/Makefile.in b/test/Makefile.in
index 451513a7474..597ef913113 100644
--- a/test/Makefile.in
+++ b/test/Makefile.in
@@ -98,9 +98,9 @@ TEST_LOCALE = C
 TEST_INTERACTIVE ?= no
 
 ifeq ($(TEST_INTERACTIVE),yes)
-TEST_RUN_ERT = --eval "(ert ${SELECTOR_ACTUAL})"
+TEST_RUN_ERT = --eval '(ert (quote ${SELECTOR_ACTUAL}))'
 else
-TEST_RUN_ERT = --batch --eval "(ert-run-tests-batch-and-exit ${SELECTOR_ACTUAL})" ${WRITE_LOG}
+TEST_RUN_ERT = --batch --eval '(ert-run-tests-batch-and-exit (quote ${SELECTOR_ACTUAL}))' ${WRITE_LOG}
 endif
 
 # Whether to run tests from .el files in preference to .elc, we do
@@ -140,8 +140,8 @@ test_module_dir := $(srcdir)/data/emacs-module
 
 all: check
 
-SELECTOR_DEFAULT = (quote (not (or (tag :expensive-test) (tag :unstable))))
-SELECTOR_EXPENSIVE = (quote (not (tag :unstable)))
+SELECTOR_DEFAULT = (not (or (tag :expensive-test) (tag :unstable)))
+SELECTOR_EXPENSIVE = (not (tag :unstable))
 SELECTOR_ALL = t
 ifdef SELECTOR
 SELECTOR_ACTUAL=$(SELECTOR)
diff --git a/test/README b/test/README
index c1dde2e0d01..e473248c9e0 100644
--- a/test/README
+++ b/test/README
@@ -42,7 +42,10 @@ except the tests tagged as expensive.
 
 If your test file contains the tests "test-foo", "test2-foo" and
 "test-foo-remote", and you want to run only the former two tests, you
-could use a selector regexp: "make <filename> SELECTOR='\"foo$$\"'".
+could use a selector regexp (note that the "$" needs to be doubled to
+protect against "make" variable expansion):
+
+    make <filename> SELECTOR='"foo$$"'
 
 Note that although the test files are always compiled (unless they set
 no-byte-compile), the source files will be run by default, to give