meson: Track portal test sources and dependencies explicitly

This moves the required files and dependencies directly into the
executable function and tracks all optional sources and dependencies in
variables.

This specifically only adds libportal_dep when have_libportal is set.

tests/meson.build

@@ -58,7 +58,10 @@ test(
   protocol: test_protocol,
 )
 
-test_backends_sources = files(
+# We build this in the tests/ subdirectory so that it can be accessed
+# via G_TEST_BUILT
+test_backends = executable(
+  'test-backends',
   'backend/test-backends.c',
   'backend/request.c',
   'backend/session.c',
@@ -76,13 +79,6 @@ test_backends_sources = files(
   'backend/settings.c',
   'backend/wallpaper.c',
   'glib-backports.c',
-)
-
-# We build this in the tests/ subdirectory so that it can be accessed
-# via G_TEST_BUILT
-test_backends = executable(
-  'test-backends',
-  test_backends_sources,
   document_portal_built_sources,
   document_portal_built_sources,
   impl_built_sources,
@@ -92,18 +88,13 @@ test_backends = executable(
   install_dir: installed_tests_dir,
 )
 
-test_portals_sources = files(
-  'test-portals.c',
-  'utils.c',
-)
-
-limited_portals_sources = files(
-  'limited-portals.c',
-  'utils.c',
-)
+portals_test_deps = []
+portals_test_sources = files()
 
 if have_libportal
-  extra_portals_sources = files(
+  portals_test_deps += [libportal_dep]
+
+  portals_test_sources += files(
     'account.c',
     'background.c',
     'camera.c',
@@ -118,19 +109,18 @@ if have_libportal
     'wallpaper.c',
     'glib-backports.c',
   )
-
-  test_portals_sources += extra_portals_sources
-  limited_portals_sources += extra_portals_sources
 endif
 
 test_portals = executable(
   'test-portals',
+  'test-portals.c',
+  'utils.c',
+  portals_test_sources,
   impl_built_sources,
   permission_store_built_sources,
   portal_built_sources,
-  test_portals_sources,
   xdp_utils_sources,
-  dependencies: [common_deps, libportal_dep, xdp_utils_deps],
+  dependencies: [common_deps, portals_test_deps, xdp_utils_deps],
   include_directories: [common_includes, xdp_utils_includes],
   c_args: [
     '-DXDG_DP_BUILDDIR="src"',
@@ -142,12 +132,14 @@ test_portals = executable(
 
 limited_portals = executable(
   'limited-portals',
+  'limited-portals.c',
+  'utils.c',
+  portals_test_sources,
   impl_built_sources,
   permission_store_built_sources,
   portal_built_sources,
-  limited_portals_sources,
   xdp_utils_sources,
-  dependencies: [common_deps, libportal_dep, xdp_utils_deps],
+  dependencies: [common_deps, portals_test_deps, xdp_utils_deps],
   include_directories: [common_includes, xdp_utils_includes],
   c_args: [
     '-DXDG_DP_BUILDDIR="src"',