diff --git a/tests/test_CacheWriter.py b/tests/test_CacheWriter.py
new file mode 100644
index 0000000000000000000000000000000000000000..b9330757e412328ce149382f35c15dd38a21e4d3
--- /dev/null
+++ b/tests/test_CacheWriter.py
@@ -0,0 +1,35 @@
+import datetime
+import io
+import pathlib
+
+import pytest
+
+from . import any_date, relpath
+import oxrlib.cache
+import oxrlib.errors
+
+CACHE_PATH = relpath('writecache')
+HISTORICAL_PATTERN = '{date}_{base}_cache.json'
+
+class TestCacheFile(oxrlib.cache.WriteCacheFile):
+    def __init__(self, path, *args, **kwargs):
+        self.path = path
+        assert args[0].startswith('w')
+
+    def open(self):
+        open_file = io.StringIO()
+        open_file.name = self.path.as_posix()
+        return open_file
+
+
+@pytest.fixture
+def dummycache():
+    cache = oxrlib.cache.CacheWriter(CACHE_PATH, file_class=TestCacheFile)
+    cache.setup(historical=HISTORICAL_PATTERN)
+    return cache
+
+def test_cache_success(dummycache, any_date):
+    base = 'USD'
+    expect_name = CACHE_PATH / HISTORICAL_PATTERN.format(date=any_date.isoformat(), base=base)
+    with dummycache.historical(any_date, base) as cache_file:
+        assert pathlib.Path(cache_file.name) == expect_name