properly implement precompressed body tests

tests/test_web_functional.py

@@ -763,14 +763,36 @@ def handler(request):
     assert 200 == resp.status
 
 
-@pytest.mark.xfail  # and had never worked
 @asyncio.coroutine
-def test_response_with_precompressed_body(loop, test_client):
+def test_response_with_precompressed_body_gzip(loop, test_client):
+
     @asyncio.coroutine
     def handler(request):
         headers = {'Content-Encoding': 'gzip'}
-        deflated_data = zlib.compress(b'mydata')
-        return web.Response(body=deflated_data, headers=headers)
+        zcomp = zlib.compressobj(wbits=16 + zlib.MAX_WBITS)
+        data = zcomp.compress(b'mydata') + zcomp.flush()
+        return web.Response(body=data, headers=headers)
+
+    app = web.Application(loop=loop)
+    app.router.add_get('/', handler)
+    client = yield from test_client(app)
+
+    resp = yield from client.get('/')
+    assert 200 == resp.status
+    data = yield from resp.read()
+    assert b'mydata' == data
+    assert resp.headers.get('Content-Encoding') == 'gzip'
+
+
+@asyncio.coroutine
+def test_response_with_precompressed_body_deflate(loop, test_client):
+
+    @asyncio.coroutine
+    def handler(request):
+        headers = {'Content-Encoding': 'deflate'}
+        zcomp = zlib.compressobj(wbits=-zlib.MAX_WBITS)
+        data = zcomp.compress(b'mydata') + zcomp.flush()
+        return web.Response(body=data, headers=headers)
 
     app = web.Application(loop=loop)
     app.router.add_get('/', handler)