almarklein · almarklein · Feb 18, 2019 · Feb 18, 2019 · Feb 18, 2019
diff --git a/asgineer/_app.py b/asgineer/_app.py
@@ -70,6 +70,25 @@ def normalize_response(response):
     return status, headers, body
 
 
+def guess_content_type_from_body(body):
+    """ Guess the content-type based of the body.
+
+    * "text/html" for str bodies starting with ``<!DOCTYPE html>`` or ``<html>``.
+    * "text/plain" for other str bodies.
+    * "application/json" for dict bodies.
+    * "application/octet-stream" otherwise.
+    """
+    if isinstance(body, str):
+        if body.startswith(("<!DOCTYPE html>", "<!doctype html>", "<html>")):
+            return "text/html"
+        else:
+            return "text/plain"
+    elif isinstance(body, dict):
+        return "application/json"
+    else:
+        return "application/octet-stream"
+
+
 class BaseApplication:
     """ Base ASGI application class.
     """
@@ -165,21 +184,20 @@ async def _handle_http(self, request, receive, send):
 
             status, headers, body = normalize_response(result)
 
+            # Make sure that there is a content type
+            if "content-type" not in headers:
+                headers["content-type"] = guess_content_type_from_body(body)
+
             # Convert the body
             if isinstance(body, bytes):
-                pass  # Make no assumptions about the content-type
+                pass
             elif isinstance(body, str):
-                if body.startswith(("<!DOCTYPE html>", "<html>")):
-                    headers.setdefault("content-type", "text/html")
-                else:
-                    headers.setdefault("content-type", "text/plain")
                 body = body.encode()
             elif isinstance(body, dict):
                 try:
                     body = json.dumps(body).encode()
                 except Exception as err:
                     raise ValueError(f"Could not JSON encode body: {err}")
-                headers.setdefault("content-type", "application/json")
             elif inspect.isasyncgen(body):
                 pass
             else:

diff --git a/asgineer/utils.py b/asgineer/utils.py
@@ -6,10 +6,10 @@
 import hashlib
 import mimetypes
 
-from ._app import normalize_response
+from ._app import normalize_response, guess_content_type_from_body
 
 
-__all__ = ["normalize_response", "make_asset_handler"]
+__all__ = ["normalize_response", "make_asset_handler", "guess_content_type_from_body"]
 
 
 def make_asset_handler(assets, max_age=0, min_compress_size=256):
@@ -92,10 +92,8 @@ async def some_handler(request):
         ctype, enc = mimetypes.guess_type(key)
         if ctype:
             ctypes[key] = ctype
-        elif isinstance(val, bytes):
-            ctypes[key] = "application/octet-stream"
         else:
-            pass  # str bodies get a content-type from Asgineer core.
+            ctypes[key] = guess_content_type_from_body(val)
 
     async def asset_handler(request, path=None):
         assert request.method in ("GET", "HEAD")

diff --git a/docs/reference.rst b/docs/reference.rst
@@ -95,6 +95,8 @@ Utility functions
 
 The ``asgineer.utils`` module provides a few utilities for common tasks.
 
+.. autofunction:: asgineer.utils.make_asset_handler
+
 .. autofunction:: asgineer.utils.normalize_response
 
-.. autofunction:: asgineer.utils.make_asset_handler
+.. autofunction:: asgineer.utils.guess_content_type_from_body
diff --git a/tests/common.py b/tests/common.py
@@ -9,7 +9,7 @@
 
 
 def get_backend():
-    return os.environ.get("ASGI_SERVER", "hypercorn").lower()
+    return os.environ.get("ASGI_SERVER", "mock").lower()
 
 
 def set_backend_from_argv():

diff --git a/tests/test_utils.py b/tests/test_utils.py
@@ -21,6 +21,7 @@ def test_make_asset_handler():
     # Make a server
     assets = {"foo.html": "bla", "foo.png": b"x" * 10000}
     assets.update({"b.xx": b"x", "t.xx": "x", "h.xx": "<html>x</html>"})
+    assets.update({"big.html": "x" * 10000, "bightml": "<html>" + "x" * 100000})
     handler = asgineer.utils.make_asset_handler(assets)
     server = make_server(asgineer.to_asgi(handler))
 
@@ -85,6 +86,20 @@ def test_make_asset_handler():
     assert r7.status == 200 and r8.status == 200
     assert len(r1.body) == 3 and len(r2.body) == 10000
 
+    # Big html files will be zipped, but must retain content type
+    for fname in ("big.html", "bightml"):
+        r = server.get(fname)
+        assert r.status == 200
+        assert r.headers.get("content-encoding", "identity") == "identity"
+        assert r.headers["content-type"] == "text/html"
+        plainbody = r.body
+
+        r = server.get(fname, headers={"accept-encoding": "gzip"})
+        assert r.status == 200
+        assert r.headers.get("content-encoding", "identity") == "gzip"
+        assert r.headers["content-type"] == "text/html"
+        assert len(r.body) < len(plainbody)
+
 
 if __name__ == "__main__":
     test_make_asset_handler()