tests: fill out coverage for new fsck features

nilmdb/fsck/fsck.py

@@ -248,23 +248,22 @@ class Fsck(object):
 
                     # Check that we can open bulkdata
                     tab = nilmdb.server.bulkdata.Table(bulk)
-                except FsckFormatError:
+                except FsckFormatError as e:
                     # If there are no files except _format, try deleting
                     # the entire stream; this may remove metadata, but
                     # it's probably unimportant.
                     files = list(os.listdir(bulk))
                     if len(files) > 1:
-                        raise
-                    if len(files) == 1 and files[0] != b'_format':
-                        raise
+                        raise FsckFormatError(f"{path}: can't load _format, "
+                                              f"but data is also present")
 
                     # Since the stream was empty, just remove it
                     self.fix_remove_stream(sid, path, bulk,
                                            "empty, with corrupted format file")
-
-                except FsckError:
-                    raise
-                except Exception as e:
+                except FsckError as e:
+                    raise e
+                except Exception as e: # pragma: no cover
+                    # No coverage because this is an unknown/unexpected error
                     raise FsckError("%s: can't open bulkdata: %s",
                                     path, str(e))
                 tab.close()
@@ -278,6 +277,7 @@ class Fsck(object):
                 fmt = pickle.load(f)
         except Exception as e:
             raise FsckFormatError(f"{path}: can't load _format file ({e})")
+
         if fmt["version"] != 3:
             raise FsckFormatError("%s: bad or unsupported bulkdata version %d",
                                   path, fmt["version"])

tests/test_fsck.py

@@ -163,3 +163,8 @@ class TestFsck(object):
             raise Exception("hi")
         with assert_raises(Exception):
             foo()
+
+        self.failmsg("test2v", "can't load _format, but data is also present")
+        self.failmsg("test2v1", "bad bulkdata table")
+        self.failmsg("test2v2", "empty, with corrupted format file", fix=False)
+        self.okmsg("test2v2", "empty, with corrupted format file")