Added new tests, new request logic, and handler file

Added new tests for alternate uses for alternate range request types.

Changed error handlnig for new request logic that simplifies the integration logic

Moved the error handler and the content range handler to their own handler file to prevent circular imports.

tests/test_static.py

@@ -86,8 +86,43 @@ def test_static_content_range_correct(static_file_path, static_file_content):
     assert response.status == 200
     assert 'Content-Length' in response.headers
     assert 'Content-Range' in response.headers
-    assert int(response.headers['Content-Length']) == 19-12
-    assert response.body == bytes(static_file_content)[12:19]
+    static_content = bytes(static_file_content)[12:19]
+    assert int(response.headers['Content-Length']) == len(static_content)
+    assert response.body == static_content
+
+
+def test_static_content_range_front(static_file_path, static_file_content):
+    app = Sanic('test_static')
+    app.static('/testing.file', static_file_path, use_content_range=True)
+
+    headers = {
+        'Range': 'bytes=12-'
+    }
+    request, response = sanic_endpoint_test(
+        app, uri='/testing.file', headers=headers)
+    assert response.status == 200
+    assert 'Content-Length' in response.headers
+    assert 'Content-Range' in response.headers
+    static_content = bytes(static_file_content)[12:]
+    assert int(response.headers['Content-Length']) == len(static_content)
+    assert response.body == static_content
+
+
+def test_static_content_range_back(static_file_path, static_file_content):
+    app = Sanic('test_static')
+    app.static('/testing.file', static_file_path, use_content_range=True)
+
+    headers = {
+        'Range': 'bytes=-12'
+    }
+    request, response = sanic_endpoint_test(
+        app, uri='/testing.file', headers=headers)
+    assert response.status == 200
+    assert 'Content-Length' in response.headers
+    assert 'Content-Range' in response.headers
+    static_content = bytes(static_file_content)[-12:]
+    assert int(response.headers['Content-Length']) == len(static_content)
+    assert response.body == static_content
 
 
 def test_static_content_range_empty(static_file_path, static_file_content):