installed tests: Allow tests to set environment variables

It's necessary sometimes for installed tests to be able to run with a
custom environment. For example, the gsocketclient-slow test requires an
LD_PRELOADed library to provide a slow connect() (this is to be added in
a followup commit).

Introduce a variable `@env@` into the installed test template, which we
can override as necessary when generating `.test` files, to run tests
prefixed with `/usr/bin/env <LIST OF VARIABLES>`.

As the only test that requires this currently lives in `gio/tests/`, we
are only hooking this up for that directory right now. If other tests in
future require this treatment, then the support can be extended at that
point.

gio/tests/meson.build

@@ -593,11 +593,21 @@ foreach test_name, extra_args : gio_tests
   source = extra_args.get('source', test_name + '.c')
   extra_sources = extra_args.get('extra_sources', [])
   install = installed_tests_enabled and extra_args.get('install', true)
+  installed_tests_env = extra_args.get('installed_tests_env', {})
 
   if install
     test_conf = configuration_data()
     test_conf.set('installed_tests_dir', installed_tests_execdir)
     test_conf.set('program', test_name)
+    test_env_override = ''
+    if installed_tests_env != {}
+      envs = []
+      foreach var, value : installed_tests_env
+         envs += '@0@=@1@'.format(var, value)
+      endforeach
+      test_env_override = '@0@ @1@ '.format(env_program.path(), ' '.join(envs))
+    endif
+    test_conf.set('env', test_env_override)
     configure_file(
       input: installed_tests_template_tap,
       output: test_name + '.test',

glib/tests/meson.build

@@ -183,6 +183,7 @@ foreach test_name, extra_args : glib_tests
     test_conf = configuration_data()
     test_conf.set('installed_tests_dir', installed_tests_execdir)
     test_conf.set('program', test_name)
+    test_conf.set('env', '')
     configure_file(
       input: installed_tests_template_tap,
       output: test_name + '.test',

gobject/tests/meson.build

@@ -77,6 +77,7 @@ foreach test_name, extra_args : gobject_tests
     test_conf = configuration_data()
     test_conf.set('installed_tests_dir', installed_tests_execdir)
     test_conf.set('program', test_name)
+    test_conf.set('env', '')
     configure_file(
       input: installed_tests_template_tap,
       output: test_name + '.test',

meson.build

@@ -1893,6 +1893,9 @@ endif
 have_bash = find_program('bash', required : false).found() # For completion scripts
 have_sh = find_program('sh', required : false).found() # For glib-gettextize
 
+# Some installed tests require a custom environment
+env_program = find_program('env', required: installed_tests_enabled)
+
 # FIXME: How to detect Solaris? https://github.com/mesonbuild/meson/issues/1578
 if host_system == 'sunos'
   glib_conf.set('_XOPEN_SOURCE_EXTENDED', 1)

template-tap.test.in

@@ -1,4 +1,4 @@
 [Test]
 Type=session
-Exec=@installed_tests_dir@/@program@ --tap
+Exec=@env@@installed_tests_dir@/@program@ --tap
 Output=TAP

tests/gobject/meson.build

@@ -66,6 +66,7 @@ foreach test_name, extra_args : gobject_tests
     test_conf = configuration_data()
     test_conf.set('installed_tests_dir', installed_tests_execdir)
     test_conf.set('program', test_name)
+    test_conf.set('env', '')
     configure_file(
       input: template,
       output: test_name + '.test',

tests/meson.build

@@ -109,6 +109,7 @@ foreach test_name, extra_args : tests
     test_conf = configuration_data()
     test_conf.set('installed_tests_dir', installed_tests_execdir)
     test_conf.set('program', test_name)
+    test_conf.set('env', '')
     configure_file(
       input: template,
       output: test_name + '.test',

tests/refcount/meson.build

@@ -36,6 +36,7 @@ foreach test_name, extra_args : refcount_tests
     test_conf = configuration_data()
     test_conf.set('installed_tests_dir', installed_tests_execdir)
     test_conf.set('program', test_name)
+    test_conf.set('env', '')
     configure_file(
       input: installed_tests_template,
       output: test_name + '.test',