tests: Search the appropriate directories for our GIR XML inputs

During "as-installed" testing, we should search the GIR_DIR for GIR XML,
instead of hard-coding that it is `${prefix}/share/gir-1.0`. This is
not the case on at least Debian, in order to make it possible to
install more than one architecture's flavour of `GLib-2.0.gir`,
which contains some architecture-specific `#define`s.

Also search GOBJECT_INTROSPECTION_DATADIR/GIR_SUFFIX (in practice
something like `/usr/share/gir-1.0` in all cases) to accommodate
distributions like Debian that move the architecture-independent
majority of GIR XML into /usr/share to avoid duplication, leaving
only the architecture-specific minority of files like `GLib-2.0.gir`
in the GIR_DIR.

Signed-off-by: Simon McVittie <smcv@collabora.com>

tests/black.sh

@@ -16,7 +16,7 @@ export TEST_REQUIRES_TOOLS="black git"
 
 run_lint () {
     # shellcheck disable=SC2046
-    black --diff --check $(git ls-files '*.py')
+    black --diff --check $(git ls-files '*.py' 'tests/lib/*.py.in')
 }
 
 # shellcheck source=tests/lint-common.sh

tests/flake8.sh

@@ -21,7 +21,7 @@ run_lint () {
     # shellcheck disable=SC2046
     flake8 \
         --max-line-length=88 --ignore="$formatting_warnings" \
-        $(git ls-files '*.py')
+        $(git ls-files '*.py' 'tests/lib/*.py.in')
 }
 
 # shellcheck source=tests/lint-common.sh

tests/lib/glibconfig.py.in

@@ -0,0 +1,29 @@
+# Copyright 2025 Simon McVittie
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+import os
+from pathlib import Path
+
+
+if "G_TEST_BUILDDIR" in os.environ:
+    # During build-time testing, we search the build tree.
+    # We can't use the value of G_TEST_BUILDDIR here because we don't
+    # know how deeply nested the current build directory is.
+    project_build_root = Path(__file__).resolve().parent.parent.parent
+
+    # Where to find GLib-2.0.gir, etc. as a list of Path, highest priority first
+    GIR_XML_SEARCH_PATHS = [
+        project_build_root / "girepository" / "introspection",
+    ]
+
+else:
+    # During as-installed testing, we search the final paths.
+
+    # This is a subset of the search path from girparser.c locate_gir(),
+    # with only the directories that are part of GLib's prefix,
+    # excluding XDG_DATA_HOME, XDG_DATA_DIRS and the hard-coded
+    # /usr/share fallback
+    GIR_XML_SEARCH_PATHS = [
+        Path(r"@glib_girdir@"),
+        Path(r"@glib_datadir@") / "gir-1.0",
+    ]

tests/lib/meson.build

@@ -0,0 +1,25 @@
+# Copyright 2024 Collabora Ltd.
+# Copyright 2025 Simon McVittie
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+install_data(
+  files(
+    'taptestrunner.py',
+    'testprogramrunner.py',
+  ),
+  install_dir: installed_tests_execdir,
+  install_tag: 'tests',
+)
+
+tests_conf = configuration_data()
+tests_conf.set('glib_datadir', glib_datadir)
+tests_conf.set('glib_girdir', glib_girdir)
+
+configure_file(
+  configuration: tests_conf,
+  input: 'glibconfig.py.in',
+  output: 'glibconfig.py',
+  install: installed_tests_enabled,
+  install_dir: installed_tests_execdir,
+  install_tag: 'tests',
+)

tests/meson.build

@@ -34,18 +34,4 @@ test(
   protocol : 'tap',
 )
 
-# TAP test runner for Python tests
-if installed_tests_enabled
-  lib_path = fs.relative_to(
-      meson.project_source_root() / python_test_libraries_path,
-      meson.current_source_dir())
-
-  install_data(
-    files(
-      lib_path / 'taptestrunner.py',
-      lib_path / 'testprogramrunner.py',
-    ),
-    install_dir: installed_tests_execdir,
-    install_tag: 'tests',
-  )
-endif
+subdir('lib')