Allow disabling installed tests

Follow what GLib does, down to the same configuration option.

Fixes: #72

json-glib/tests/meson.build

@@ -31,7 +31,9 @@ test_data = [
 installed_test_bindir = json_libexecdir / 'installed-tests' / json_api_name
 installed_test_datadir = json_datadir / 'installed-tests' / json_api_name
 
-install_data(test_data, install_dir: installed_test_bindir)
+if get_option('installed_tests')
+  install_data(test_data, install_dir: installed_test_bindir)
+endif
 
 foreach t: tests
   installed_test = '@0@.test'.format(t)
@@ -46,14 +48,14 @@ foreach t: tests
       '--outdir=@OUTDIR@',
       '--outfile=@0@'.format(installed_test),
     ],
-    install: true,
+    install: get_option('installed_tests'),
     install_dir: installed_test_datadir,
   )
 
   exe = executable(
     t, '@0@.c'.format(t),
     c_args: json_c_args,
-    install: true,
+    install: get_option('installed_tests'),
     install_dir: installed_test_bindir,
     dependencies: [ json_glib_dep, ],
   )

meson.build

@@ -191,6 +191,7 @@ summary({
     'Documentation': build_doc,
     'Manual pages': get_option('man'),
     'Tests': get_option('tests'),
+    'Installed tests': get_option('installed_tests'),
     'Conformance tests': get_option('conformance'),
   },
   section: 'Build',

meson_options.txt

@@ -27,3 +27,6 @@ option('conformance',
 option('nls',
        type: 'feature', value: 'auto', yield: true,
        description: 'Enable native language support (translations)')
+option('installed_tests',
+       type: 'boolean', value: true,
+       description: 'Enable installed tests')