Allow installing unit tests

Closes #9343

See that issue for motivation.

Installing these is disabled by default, but we enable it (and the
additional output we want isntall these too so as not to clutter the
existing ones) to use in cross builds and dev shells.

Makefile.config.in

@@ -28,6 +28,8 @@ SODIUM_LIBS = @SODIUM_LIBS@
 SQLITE3_LIBS = @SQLITE3_LIBS@
 bash = @bash@
 bindir = @bindir@
+checkbindir = @checkbindir@
+checklibdir = @checklibdir@
 datadir = @datadir@
 datarootdir = @datarootdir@
 doc_generate = @doc_generate@
@@ -48,4 +50,5 @@ sysconfdir = @sysconfdir@
 system = @system@
 ENABLE_BUILD = @ENABLE_BUILD@
 ENABLE_TESTS = @ENABLE_TESTS@
+INSTALL_UNIT_TESTS = @INSTALL_UNIT_TESTS@
 internal_api_docs = @internal_api_docs@

configure.ac

@@ -167,6 +167,18 @@ AC_ARG_ENABLE(tests, AS_HELP_STRING([--disable-tests],[Do not build the tests]),
   ENABLE_TESTS=$enableval, ENABLE_TESTS=yes)
 AC_SUBST(ENABLE_TESTS)
 
+AC_ARG_ENABLE(install-unit-tests, AS_HELP_STRING([--enable-install-unit-tests],[Install the unit tests for running later (default no)]),
+  INSTALL_UNIT_TESTS=$enableval, INSTALL_UNIT_TESTS=no)
+AC_SUBST(INSTALL_UNIT_TESTS)
+
+AC_ARG_WITH(check-bin-dir, AS_HELP_STRING([--with-check-bin-dir=PATH],[path to install unit tests for running later (defaults to $libexecdir/nix)]),
+  checkbindir=$withval, checkbindir=$libexecdir/nix)
+AC_SUBST(checkbindir)
+
+AC_ARG_WITH(check-lib-dir, AS_HELP_STRING([--with-check-lib-dir=PATH],[path to install unit tests for running later (defaults to $libdir)]),
+  checklibdir=$withval, checklibdir=$libdir)
+AC_SUBST(checklibdir)
+
 # Building without API docs is the default as Nix' C++ interfaces are internal and unstable.
 AC_ARG_ENABLE(internal_api_docs, AS_HELP_STRING([--enable-internal-api-docs],[Build API docs for Nix's internal unstable C++ interfaces]),
   internal_api_docs=$enableval, internal_api_docs=no)

flake.nix

@@ -164,6 +164,10 @@
 
         testConfigureFlags = [
           "RAPIDCHECK_HEADERS=${lib.getDev rapidcheck}/extras/gtest/include"
+        ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
+          "--enable-install-unit-tests"
+          "--with-check-bin-dir=${builtins.placeholder "check"}/bin"
+          "--with-check-lib-dir=${builtins.placeholder "check"}/lib"
         ];
 
         internalApiDocsConfigureFlags = [
@@ -404,7 +408,8 @@
             src = nixSrc;
             VERSION_SUFFIX = versionSuffix;
 
-            outputs = [ "out" "dev" "doc" ];
+            outputs = [ "out" "dev" "doc" ]
+              ++ lib.optional (currentStdenv.hostPlatform != currentStdenv.buildPlatform) "check";
 
             nativeBuildInputs = nativeBuildDeps;
             buildInputs = buildDeps
@@ -710,7 +715,8 @@
           stdenv.mkDerivation {
             name = "nix";
 
-            outputs = [ "out" "dev" "doc" ];
+            outputs = [ "out" "dev" "doc" ]
+              ++ lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) "check";
 
             nativeBuildInputs = nativeBuildDeps
               ++ lib.optional stdenv.cc.isClang pkgs.buildPackages.bear

src/libexpr/tests/local.mk

@@ -6,7 +6,11 @@ libexpr-tests_NAME := libnixexpr-tests
 
 libexpr-tests_DIR := $(d)
 
+ifeq ($(INSTALL_UNIT_TESTS), yes)
+  libexpr-tests_INSTALL_DIR := $(checkbindir)
+else
   libexpr-tests_INSTALL_DIR :=
+endif
 
 libexpr-tests_SOURCES := \
     $(wildcard $(d)/*.cc) \

src/libstore/tests/local.mk

@@ -6,7 +6,11 @@ libstore-tests-exe_NAME = libnixstore-tests
 
 libstore-tests-exe_DIR := $(d)
 
+ifeq ($(INSTALL_UNIT_TESTS), yes)
+  libstore-tests-exe_INSTALL_DIR := $(checkbindir)
+else
   libstore-tests-exe_INSTALL_DIR :=
+endif
 
 libstore-tests-exe_LIBS = libstore-tests
 
@@ -18,7 +22,11 @@ libstore-tests_NAME = libnixstore-tests
 
 libstore-tests_DIR := $(d)
 
+ifeq ($(INSTALL_UNIT_TESTS), yes)
+  libstore-tests_INSTALL_DIR := $(checklibdir)
+else
   libstore-tests_INSTALL_DIR :=
+endif
 
 libstore-tests_SOURCES := $(wildcard $(d)/*.cc)
 

src/libutil/tests/local.mk

@@ -6,7 +6,11 @@ libutil-tests-exe_NAME = libnixutil-tests
 
 libutil-tests-exe_DIR := $(d)
 
+ifeq ($(INSTALL_UNIT_TESTS), yes)
+  libutil-tests-exe_INSTALL_DIR := $(checkbindir)
+else
   libutil-tests-exe_INSTALL_DIR :=
+endif
 
 libutil-tests-exe_LIBS = libutil-tests
 
@@ -18,7 +22,11 @@ libutil-tests_NAME = libnixutil-tests
 
 libutil-tests_DIR := $(d)
 
+ifeq ($(INSTALL_UNIT_TESTS), yes)
+  libutil-tests_INSTALL_DIR := $(checklibdir)
+else
   libutil-tests_INSTALL_DIR :=
+endif
 
 libutil-tests_SOURCES := $(wildcard $(d)/*.cc)