Added test to show that build should fail if non-existent file is added

tests/test_build.py

@@ -69,4 +69,15 @@ def test_patch(wrapper):
 
     rc, _, _ = run_make(wrapper, "cellinstall", __DEBUG_VERSION=MODULE_VERSION)
     assert rc == 0
-    assert any((wrapper / "cellMods").glob("**/*.db"))
\ No newline at end of file
+    assert any((wrapper / "cellMods").glob("**/*.db"))
+
+
+@pytest.mark.parametrize(
+    "wrapper",
+    [{"templates": "", "sources": "", "dbds": "nonexistent.dbd", "headers": ""}],
+    indirect=True,
+)
+def test_missing_file(wrapper):
+    rc, _, errs = run_make(wrapper, "build", __DEBUG_VERSION=MODULE_VERSION)
+    assert "No rule to make target `../nonexistent.dbd'" in errs.decode("utf-8")
+    assert rc == 2