Change detect_build_system to not default to manual

We do not want a manual build system if there is no morphology,
since building with a no-op manual build system just hides the
fact that the chunk can't be built because a morphology is missing.

2 files changed, 4 insertions, 6 deletions

diff --git a/morphlib/buildsystem.py b/morphlib/buildsystem.py
index 8b71a640..a048d881 100644
--- a/morphlib/buildsystem.py
+++ b/morphlib/buildsystem.py
@@ -129,16 +129,14 @@ build_systems = [
 def detect_build_system(srcdir):
     '''Automatically detect the build system, if possible.
     
-    If the build system cannot be detected automatically, then the manual
-    build system is used instead.
+    If the build system cannot be detected automatically, return None.
     
     '''
     
     for bs in build_systems:
         if bs.used_by_project(srcdir):
             return bs
-    return ManualBuildSystem()
-
+    return None
 
 
 def lookup_build_system(name):
diff --git a/morphlib/buildsystem_tests.py b/morphlib/buildsystem_tests.py
index 6d426d8c..2d688922 100644
--- a/morphlib/buildsystem_tests.py
+++ b/morphlib/buildsystem_tests.py
@@ -121,10 +121,10 @@ class DetectBuildSystemTests(unittest.TestCase):
     def tearDown(self):
         shutil.rmtree(self.tempdir)
 
-    def test_autodetects_manual(self):
+    def test_does_not_autodetect_manual(self):
         create_manual_project(self.tempdir)
         bs = morphlib.buildsystem.detect_build_system(self.tempdir)
-        self.assertEqual(type(bs), morphlib.buildsystem.ManualBuildSystem)
+        self.assertEqual(bs, None)
 
     def test_autodetects_autotools(self):
         create_autotools_project(self.tempdir)