backends: add a new "none" backend

It can only be used for projects that don't have any rules at all, i.e.
they are purely using Meson to:

- configure files
- run (script?) tests
- install files that exist by the end of the setup stage

This can be useful e.g. for Meson itself, a pure python project.

2 files changed, 18 insertions, 0 deletions

diff --git a/unittests/baseplatformtests.py b/unittests/baseplatformtests.py
index d83ef3f..9e55f6e 100644
--- a/unittests/baseplatformtests.py
+++ b/unittests/baseplatformtests.py
@@ -70,6 +70,7 @@ class BasePlatformTests(TestCase):
             self.uninstall_command = get_backend_commands(self.backend)
         # Test directories
         self.common_test_dir = os.path.join(src_root, 'test cases/common')
+        self.python_test_dir = os.path.join(src_root, 'test cases/python')
         self.rust_test_dir = os.path.join(src_root, 'test cases/rust')
         self.vala_test_dir = os.path.join(src_root, 'test cases/vala')
         self.framework_test_dir = os.path.join(src_root, 'test cases/frameworks')
diff --git a/unittests/platformagnostictests.py b/unittests/platformagnostictests.py
index 39965c6..fce115d 100644
--- a/unittests/platformagnostictests.py
+++ b/unittests/platformagnostictests.py
@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import json
 import os
 import tempfile
 import subprocess
@@ -121,3 +122,19 @@ class PlatformAgnosticTests(BasePlatformTests):
                     '''))
             subprocess.check_call(self.wrap_command + ['update-db'], cwd=testdir)
             self.init(testdir, workdir=testdir)
+
+    def test_none_backend(self):
+        testdir = os.path.join(self.python_test_dir, '7 install path')
+
+        self.init(testdir, extra_args=['--backend=none'], override_envvars={'NINJA': 'absolutely false command'})
+        self.assertPathDoesNotExist(os.path.join(self.builddir, 'build.ninja'))
+
+        self.run_tests(inprocess=True, override_envvars={})
+
+        out = self._run(self.meson_command + ['install', f'--destdir={self.installdir}'], workdir=self.builddir)
+        self.assertNotIn('Only ninja backend is supported to rebuild the project before installation.', out)
+
+        with open(os.path.join(testdir, 'test.json'), 'rb') as f:
+            dat = json.load(f)
+        for i in dat['installed']:
+            self.assertPathExists(os.path.join(self.installdir, i['file']))