Unit tests Recipe download feature

Currently unit tests the following:

- `Recipe.download_if_necessary()`
- `Recipe.download()`

Next up is `Recipe.download_file()`. This is more difficult and will be
addressed in subsequent pull request.

pythonforandroid/recipe.py

@@ -156,10 +156,10 @@ def report_hook(index, blksize, size):
             while True:
                 try:
                     urlretrieve(url, target, report_hook)
-                except OSError as e:
+                except OSError:
                     attempts += 1
                     if attempts >= 5:
-                        raise e
+                        raise
                     stdout.write('Download failed retrying in a second...')
                     time.sleep(1)
                     continue

tests/test_recipe.py

@@ -2,10 +2,28 @@
 import types
 import unittest
 import warnings
+import mock
+from backports import tempfile
 from pythonforandroid.build import Context
 from pythonforandroid.recipe import Recipe, import_recipe
 
 
+def patch_logger(level):
+    return mock.patch('pythonforandroid.recipe.{}'.format(level))
+
+
+def patch_logger_info():
+    return patch_logger('info')
+
+
+def patch_logger_debug():
+    return patch_logger('debug')
+
+
+class DummyRecipe(Recipe):
+    pass
+
+
 class TestRecipe(unittest.TestCase):
 
     def test_recipe_dirs(self):
@@ -58,3 +76,49 @@ def test_import_recipe(self):
             module = import_recipe(name, pathname)
         assert module is not None
         assert recorded_warnings == []
+
+    def test_download_if_necessary(self):
+        """
+        Download should happen via `Recipe.download()` only if the recipe
+        specific environment variable is not set.
+        """
+        # download should happen as the environment variable is not set
+        recipe = DummyRecipe()
+        with mock.patch.object(Recipe, 'download') as m_download:
+            recipe.download_if_necessary()
+        assert m_download.call_args_list == [mock.call()]
+        # after setting it the download should be skipped
+        env_var = 'P4A_test_recipe_DIR'
+        env_dict = {env_var: '1'}
+        with mock.patch.object(Recipe, 'download') as m_download, mock.patch.dict(os.environ, env_dict):
+            recipe.download_if_necessary()
+        assert m_download.call_args_list == []
+
+    def test_download(self):
+        """
+        Verifies the actual download gets triggered when the URL is set.
+        """
+        # test with no URL set
+        recipe = DummyRecipe()
+        with patch_logger_info() as m_info:
+            recipe.download()
+        assert m_info.call_args_list == [
+            mock.call('Skipping test_recipe download as no URL is set')]
+        # when the URL is set `Recipe.download_file()` should be called
+        filename = 'Python-3.7.4.tgz'
+        url = 'https://www.python.org/ftp/python/3.7.4/{}'.format(filename)
+        recipe._url = url
+        recipe.ctx = Context()
+        with (
+                patch_logger_debug()) as m_debug, (
+                mock.patch.object(Recipe, 'download_file')) as m_download_file, (
+                mock.patch('pythonforandroid.recipe.sh.touch')) as m_touch, (
+                tempfile.TemporaryDirectory()) as temp_dir:
+            recipe.ctx.setup_dirs(temp_dir)
+            recipe.download()
+        assert m_download_file.call_args_list == [mock.call(url, filename)]
+        assert m_debug.call_args_list == [
+            mock.call(
+                'Downloading test_recipe from '
+                'https://www.python.org/ftp/python/3.7.4/Python-3.7.4.tgz')]
+        assert m_touch.call_count == 1

tox.ini

@@ -8,6 +8,7 @@ deps =
     pytest
     virtualenv
     py3: coveralls
+    backports.tempfile
 # makes it possible to override pytest args, e.g.
 # tox -- tests/test_graph.py
 commands = pytest {posargs:tests/}