tests: add coverage for helpers

src/ocrmypdf/api.py

@@ -19,6 +19,7 @@ import logging
 import os
 import sys
 import warnings
+from contextlib import suppress
 from enum import IntEnum
 from pathlib import Path
 from typing import Dict, List, Optional
@@ -46,7 +47,7 @@ class TqdmConsole:
             tqdm.write(msg.rstrip(), end='\n', file=self.file)
 
     def flush(self):
-        if hasattr(self.file, "flush"):
+        with suppress(AttributeError):
             self.file.flush()
 
 

src/ocrmypdf/helpers.py

@@ -104,28 +104,36 @@ def is_file_writable(test_file):
     can replace it atomically. Before doing the OCR work, make sure
     the location is writable.
     """
-    p = Path(test_file)
-
-    if p.is_symlink():
-        p = p.resolve(strict=False)
-
-    # p.is_file() throws an exception in some cases
-    if p.exists() and p.is_file():
-        return os.access(
-            os.fspath(p),
-            os.W_OK,
-            effective_ids=(os.access in os.supports_effective_ids),
-        )
-    else:
-        try:
-            fp = p.open('wb')
-        except OSError:
-            return False
+    try:
+        if not isinstance(test_file, Path):
+            p = Path(test_file)
         else:
-            fp.close()
-            with suppress(OSError):
-                p.unlink()
-        return True
+            p = test_file
+
+        if p.is_symlink():
+            p = p.resolve(strict=False)
+
+        # p.is_file() throws an exception in some cases
+        if p.exists() and p.is_file():
+            return os.access(
+                os.fspath(p),
+                os.W_OK,
+                effective_ids=(os.access in os.supports_effective_ids),
+            )
+        else:
+            try:
+                fp = p.open('wb')
+            except OSError:
+                return False
+            else:
+                fp.close()
+                with suppress(OSError):
+                    p.unlink()
+            return True
+    except (EnvironmentError, RuntimeError) as e:
+        log.debug(e)
+        log.error(str(e))
+        return False
 
 
 def deprecated(func):

tests/test_helpers.py

@@ -0,0 +1,97 @@
+# © 2019 James R. Barlow: github.com/jbarlow83
+#
+# This file is part of OCRmyPDF.
+#
+# OCRmyPDF is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# OCRmyPDF is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+
+import logging
+import multiprocessing
+from pathlib import Path
+from unittest.mock import MagicMock
+
+import pytest
+
+import ocrmypdf.helpers as helpers
+
+
+class TestSafeSymlink:
+    def test_safe_symlink_link_self(self, tmp_path, caplog):
+        helpers.safe_symlink(tmp_path / 'self', tmp_path / 'self')
+        assert caplog.record_tuples[0][1] == logging.WARNING
+
+    def test_safe_symlink_overwrite(self, tmp_path):
+        (tmp_path / 'regular_file').touch()
+        with pytest.raises(FileExistsError):
+            helpers.safe_symlink(tmp_path / 'input', tmp_path / 'regular_file')
+
+    def test_safe_symlink_relink(self, tmp_path):
+        (tmp_path / 'regular_file_a').touch()
+        (tmp_path / 'regular_file_b').write_bytes(b'ABC')
+        (tmp_path / 'link').symlink_to(tmp_path / 'regular_file_a')
+        helpers.safe_symlink(tmp_path / 'regular_file_b', tmp_path / 'link')
+        assert (tmp_path / 'link').samefile(tmp_path / 'regular_file_b') or (
+            tmp_path / 'link'
+        ).read_bytes() == b'ABC'
+
+
+def test_no_cpu_count(monkeypatch):
+    def cpu_count_raises():
+        raise NotImplementedError()
+
+    monkeypatch.setattr(multiprocessing, 'cpu_count', cpu_count_raises)
+    with pytest.warns(expected_warning=UserWarning):
+        assert helpers.available_cpu_count() == 1
+
+
+def test_deprecated():
+    @helpers.deprecated
+    def old_function():
+        return 42
+
+    with pytest.warns(expected_warning=DeprecationWarning):
+        assert old_function() == 42
+
+
+class TestFileIsWritable:
+    @pytest.fixture
+    def non_existent(self, tmp_path):
+        return tmp_path / 'nofile'
+
+    @pytest.fixture
+    def basic_file(self, tmp_path):
+        basic = tmp_path / 'basic'
+        basic.touch()
+        return basic
+
+    def test_plain(self, non_existent):
+        assert helpers.is_file_writable(non_existent)
+
+    def test_symlink_loop(self, tmp_path):
+        loop = tmp_path / 'loop'
+        loop.symlink_to(loop)
+        assert not helpers.is_file_writable(loop)
+
+    def test_chmod(self, basic_file):
+        assert helpers.is_file_writable(basic_file)
+        basic_file.chmod(0o400)
+        assert not helpers.is_file_writable(basic_file)
+        basic_file.chmod(0o000)
+        assert not helpers.is_file_writable(basic_file)
+
+    def test_permission_error(self, basic_file):
+        pathmock = MagicMock(spec_set=basic_file)
+        pathmock.is_symlink.return_value = False
+        pathmock.exists.return_value = True
+        pathmock.is_file.side_effect = PermissionError
+        assert not helpers.is_file_writable(pathmock)