TDD

cachecontrol/streaming_cache.py

@@ -51,6 +51,34 @@ def close(self):
     # to make it easier to use.
 
 
+CACHE = []
+
+
+class ExampleCache:
+    class WriteHandle:
+        def write(self, b):
+            global CACHE
+            CACHE.append(b)
+
+        def commit(self):
+            pass
+
+        def close(self):
+            pass
+
+    def open_read(self, key):
+        return io.BytesIO(CACHE.pop(0))
+
+    def open_write(self, key, expires=None):
+        return self.WriteHandle()
+
+    def delete(self, key):
+        pass
+
+    def close(self):
+        '''Cleanup any temporary files, database connections etc.'''
+        pass
+'''
 # An example to use while prototyping
 class ExampleCache:
     # Why is ExampleCache.data not a dict[str, io.BytesIO]?
@@ -88,3 +116,4 @@ def delete(self, key):
 
     def close(self):
         pass
+'''

tests/test_streaming_cache.py

@@ -0,0 +1,30 @@
+from contextlib import closing
+from cachecontrol.streaming_cache import ExampleCache
+import pytest
+
+
+@pytest.mark.parametrize('v', [b'fizz', b'buzz'])
+def test_read_returns_what_you_wrote(v):
+    with closing(ExampleCache()) as cache:
+        with closing(cache.open_write('foo')) as w:
+            w.write(v)
+            w.commit()
+        with closing(cache.open_read('foo')) as r:
+            got = r.read()
+    assert got == v
+
+
+def test_cache_remembers_more_than_one_value():
+    with closing(ExampleCache()) as cache:
+        with closing(cache.open_write('foo')) as w:
+            w.write(b'one')
+            w.commit()
+        with closing(cache.open_write('bar')) as w:
+            w.write(b'two')
+            w.commit()
+        with closing(cache.open_read('foo')) as r:
+            got = r.read()
+        assert got == b'one'
+        with closing(cache.open_read('bar')) as r:
+            got = r.read()
+        assert got == b'two'