meson: Properly find where other GStreamer plugins are when using subprojects

tests/check/getpluginsdir

@@ -0,0 +1,25 @@
+#!/usr/bin/env python3
+
+import os
+import sys
+import subprocess
+
+builddir = os.environ['MESON_BUILD_ROOT']
+
+res = ''
+args = sys.argv[1:]
+for i in range(0, len(args), 2):
+    project = args[i]
+    pkg_name = args[i + 1]
+    path = os.path.join(builddir, 'subprojects', project)
+    if os.path.exists(path):
+        res += ':' + path
+    else:
+        try:
+            res += ':' + subprocess.check_output(['pkg-config',
+                                                  '--variable=pluginsdir',
+                                                  pkg_name]).decode()
+        except subprocess.CalledProcessError:
+            exit(1)
+
+print(res.strip(":"))

tests/check/meson.build

@@ -32,13 +32,13 @@ test_defines = [
   '-DGST_USE_UNSTABLE_API',
 ]
 
-runcmd = run_command('pkg-config', '--variable=pluginsdir', 'gstreamer-1.0',
-        'gstreamer-plugins-base-1.0', 'gstreamer-plugins-bad-1.0')
+getpluginsdir = find_program('getpluginsdir')
+runcmd = run_command(getpluginsdir, 'gstreamer', 'gstreamer-' + apiversion,
+        'gst-plugins-base', 'gstreamer-plugins-base-' + apiversion,
+        'gst-plugins-bad', 'gstreamer-plugins-bad-' + apiversion)
 if runcmd.returncode() == 0
-    needed_plugins_dirs = meson.build_root() + 'plugins/nle'
-    foreach path: runcmd.stdout().strip().split(' ')
-        needed_plugins_dirs = needed_plugins_dirs + ':' + path
-    endforeach
+    needed_plugins_dirs = runcmd.stdout().strip() + ':' + meson.build_root() + '/plugins/nle'
+    message('Using GStreamer plug-ins in ' + needed_plugins_dirs)
 else
   error('Could not determine GStreamer core plugins directory for unit tests.')
 endif