loaders: Initial commit.

oxrlib/loaders.py

@@ -0,0 +1,9 @@
+class FileCache:
+    def __init__(self, dir_path, filename_pattern):
+        self.dir_path = dir_path
+        self.pattern = filename_pattern
+
+    def historical(self, date, base):
+        path = self.dir_path / self.pattern.format(date=date.isoformat(), base=base)
+        return path.open()
+

tests/__init__.py

@@ -2,5 +2,5 @@ import pathlib
 
 TEST_DIR = pathlib.Path(__file__).parent
 
-def relpath(path):
-    return TEST_DIR / pathlib.Path(path)
+def relpath(*parts):
+    return TEST_DIR / pathlib.Path(*parts)

tests/test_loaders.py

@@ -0,0 +1,36 @@
+import datetime
+import pathlib
+
+import pytest
+
+from . import relpath
+import oxrlib.loaders
+
+CACHE_PATH = relpath('filecache')
+CACHE_PATTERN = '{date}_{base}_cache.json'
+
+@pytest.fixture
+def dummycache():
+    return oxrlib.loaders.FileCache(CACHE_PATH, CACHE_PATTERN)
+
+@pytest.mark.parametrize('date,base', [
+    (datetime.date(1999, 2, 1), 'USD'),
+    (datetime.date(1999, 3, 1), 'EUR'),
+])
+def test_cache_success(dummycache, date, base):
+    expect_name = CACHE_PATH / CACHE_PATTERN.format(date=date.isoformat(), base=base)
+    with dummycache.historical(date, base) as cache_file:
+        assert pathlib.Path(cache_file.name) == expect_name
+
+@pytest.mark.parametrize('date,base', [
+    (datetime.date(1999, 2, 1), 'EUR'),
+    (datetime.date(1999, 3, 1), 'USD'),
+])
+def test_cache_not_found(dummycache, date, base):
+    try:
+        cache_file = dummycache.historical(date, base)
+    except FileNotFoundError:
+        pass
+    else:
+        cache_file.close()
+        assert False, "cache file found when unexpected"