Add test for pkgconfig generation and usage.

This builds a project with pkg-config file, installs it and then
builds a second project that uses that dependency and runs the result.

run_unittests.py

@@ -585,10 +585,11 @@ def clean(self):
     def run_tests(self):
         self._run(self.test_command, workdir=self.builddir)
 
-    def install(self):
+    def install(self, *, use_destdir=True):
         if self.backend is not Backend.ninja:
             raise unittest.SkipTest('{!r} backend can\'t install files'.format(self.backend.name))
-        os.environ['DESTDIR'] = self.installdir
+        if use_destdir:
+            os.environ['DESTDIR'] = self.installdir
         self._run(self.install_command, workdir=self.builddir)
 
     def uninstall(self):
@@ -2712,6 +2713,29 @@ def test_old_gnome_module_codepaths(self):
         self.build()
         mesonbuild.modules.gnome.native_glib_version = None
 
+    @unittest.skipIf(shutil.which('pkg-config') is None, 'Pkg-config not found.')
+    def test_pkgconfig_usage(self):
+        testdir1 = os.path.join(self.unit_test_dir, '24 pkgconfig usage/dependency')
+        testdir2 = os.path.join(self.unit_test_dir, '24 pkgconfig usage/dependee')
+        with tempfile.TemporaryDirectory() as tempdirname:
+            self.init(testdir1, ['--prefix=' + tempdirname, '--libdir=lib'], default_args=False)
+            self.install(use_destdir=False)
+            shutil.rmtree(self.builddir)
+            os.mkdir(self.builddir)
+            pkg_dir = os.path.join(tempdirname, 'lib/pkgconfig')
+            self.assertTrue(os.path.exists(os.path.join(pkg_dir, 'libpkgdep.pc')))
+            lib_dir = os.path.join(tempdirname, 'lib')
+            os.environ['PKG_CONFIG_PATH'] = pkg_dir
+            self.init(testdir2)
+            self.build()
+            myenv = os.environ.copy()
+            myenv['LD_LIBRARY_PATH'] = lib_dir
+            self.assertTrue(os.path.isdir(lib_dir))
+            self.assertTrue(os.path.isfile(os.path.join(lib_dir, 'libpkgdep.so')))
+            test_exe = os.path.join(self.builddir, 'pkguser')
+            self.assertTrue(os.path.isfile(test_exe))
+            subprocess.check_call(test_exe, env=myenv)
+
 
 class LinuxArmCrossCompileTests(BasePlatformTests):
     '''

test cases/unit/24 pkgconfig usage/dependee/meson.build

@@ -0,0 +1,7 @@
+project('pkgconfig user', 'c')
+
+pkgdep = dependency('libpkgdep')
+
+executable('pkguser', 'pkguser.c',
+  dependencies : pkgdep)
+

test cases/unit/24 pkgconfig usage/dependee/pkguser.c

@@ -0,0 +1,6 @@
+#include<pkgdep.h>
+
+int main(int argc, char **argv) {
+    int res = pkgdep();
+    return res != 99;
+}

test cases/unit/24 pkgconfig usage/dependency/meson.build

@@ -0,0 +1,24 @@
+project('pkgconfig dep', 'c', 
+  version : '1.0.0')
+
+# This is not used in the code, only to check that it does not
+# leak out to --libs.
+glib_dep = dependency('glib-2.0')
+
+pkgconfig = import('pkgconfig')
+
+intlib = static_library('libpkgdep-int', 'privatelib.c')
+intdep = declare_dependency(link_with : intlib)
+
+lib = shared_library('pkgdep', 'pkgdep.c',
+  dependencies : [glib_dep, intdep],
+  install : true)
+
+install_headers('pkgdep.h')
+
+pkgconfig.generate(
+  filebase : 'libpkgdep',
+  name : 'Libpkgdep',
+  description : 'Sample pkgconfig dependency library',
+  version : meson.project_version(),
+  libraries : lib)

test cases/unit/24 pkgconfig usage/dependency/pkgdep.c

@@ -0,0 +1,7 @@
+#include<pkgdep.h>
+
+int internal_thingy();
+
+int pkgdep() {
+    return internal_thingy();
+}

test cases/unit/24 pkgconfig usage/dependency/pkgdep.h

@@ -0,0 +1,3 @@
+#pragma once
+
+int pkgdep();

test cases/unit/24 pkgconfig usage/dependency/privatelib.c

@@ -0,0 +1,3 @@
+int internal_thingy() {
+    return 99;
+}