Additional tests

.gitignore

@@ -10,6 +10,7 @@
 /tests/data/from_list.star
 /tests/data/test_overwrite_flag.star
 /tests/data/test_write_with_float_format.star
+/tests/data/test_overwrite_backup.star
 /build/
 /dist/
 /m2relion/

src/starfile/__init__.py

@@ -1 +1 @@
-from .functions import read, write
+from .functions import read, write, to_string

src/starfile/writer.py

@@ -33,6 +33,8 @@ def __init__(
 
         if filename is not None:
             self.filename = Path(filename)
+        else:
+            self.filename = None
         self.float_format = float_format
         self.sep = separator
         self.na_rep = na_rep
@@ -69,7 +71,7 @@ def lines(self) -> Generator[str, None, None]:
 
     def write(self):
         if self.filename is None:
-            raise Exception('Cannot write nameless file!')
+            raise ValueError('Cannot write nameless file!')
         with open(self.filename, mode='w+') as f:
             f.writelines(line + '\n' for line in self.lines())
 
@@ -96,7 +98,7 @@ def data_block_generator(self) -> Generator[str, None, None]:
                     yield line
 
     def backup_if_file_exists(self):
-        if self.filename.exists():
+        if self.filename and self.filename.exists():
             new_name = self.filename.name + '~'
             backup_path = self.filename.resolve().parent / new_name
             if backup_path.exists():

tests/test_functional_interface.py

@@ -47,3 +47,11 @@ def test_read_non_existent_file():
 
     with pytest.raises(FileNotFoundError):
         starfile.read(f)
+
+
+def test_generate_string():
+    star_string = starfile.to_string(test_df)
+    output_file = test_data_directory / "test_write.star"
+    starfile.write(test_df, output_file, overwrite=True)
+    with open(output_file, "r") as f:
+        assert f.read() == star_string

tests/test_read_write_round_trip.py

@@ -42,8 +42,8 @@ def test_round_trip_postprocess(tmp_path):
             assert _actual == _expected
 
 
-def test_write_read_write_read():
-    filename = 'tmp.star'
+def test_write_read_write_read(tmp_path):
+    filename = tmp_path / 'tmp.star'
     df_a = pd.DataFrame({'a': [0, 1], 'b': [2, 3]})
     starfile.write(df_a, filename)
 

tests/test_writing.py

@@ -127,3 +127,8 @@ def test_string_quoting_simple_datablock(quote_character, quote_all_strings,num_
 
     s = StarParser(filename)
     assert o == s.data_blocks[""]
+
+
+def test_no_filename_error():
+    with pytest.raises(ValueError):
+        StarWriter(test_df).write()