meson: add a couple of expected-to-fail tests

Initial set of tests verifying we fail when trying to load:

a) a non-existing configuration
b) a non-regular file configuration (e.g. a directory)
c) configuration exists, but has no top-level 'bar' entry

meson.build

@@ -105,7 +105,7 @@ f00bar = executable(
   install: true,
   install_rpath: '$ORIGIN/../' + get_option('libdir') + '/f00bar')
 
-test('f00bar-is-executable', f00bar, args: ['--version'])
+subdir('test')
 
 install_headers(
   'color.h',

test/meson.build

@@ -0,0 +1,9 @@
+test('is-executable', f00bar, args: ['--version'])
+
+pwd = meson.current_source_dir()
+
+# Configuratoin validation tests
+test('no-config', f00bar, args: ['-c', 'xyz'], should_fail: true)
+test('config-isnt-file', f00bar, args: ['-c', '.'], should_fail: true)
+test('config-no-bar', f00bar, args: ['-c', join_paths(pwd, 'no-bar.yml')],
+     should_fail: true)

test/no-bar.yml

@@ -0,0 +1,3 @@
+top-level-isnt-bar:
+  hello: world
+