diff --git a/spiderweb/tests/test_middleware.py b/spiderweb/tests/test_middleware.py
index e2c4199..5ffedaa 100644
--- a/spiderweb/tests/test_middleware.py
+++ b/spiderweb/tests/test_middleware.py
@@ -23,8 +23,9 @@ from spiderweb.tests.views_for_tests import (
     form_csrf_exempt,
     form_view_without_csrf,
     text_view,
-    unauthorized_view,
+    unauthorized_view, file_view,
 )
+from spiderweb.middleware.gzip import GzipMiddleware, CheckValidGzipMinimumLength, CheckValidGzipCompressionLevel
 
 
 def index(request):
@@ -349,6 +350,67 @@ def test_unused_post_process_middleware():
     assert len(app.middleware) == 0
 
 
+class TestGzipMiddleware:
+    middleware = {"middleware": ["spiderweb.middleware.gzip.GzipMiddleware"]}
+
+    def test_not_enabled_on_small_response(self):
+        app, environ, start_response = setup(
+            **self.middleware,
+            gzip_minimum_response_length=500,
+        )
+        app.add_route("/", text_view)
+
+        environ["HTTP_USER_AGENT"] = "hi"
+        environ["REMOTE_ADDR"] = "/"
+        environ["REQUEST_METHOD"] = "GET"
+
+        assert app(environ, start_response) == [bytes("Hi!", DEFAULT_ENCODING)]
+        assert "Content-Encoding" not in start_response.get_headers()
+
+    def test_changing_minimum_response_length(self):
+        app, environ, start_response = setup(
+            **self.middleware,
+            gzip_minimum_response_length=1,
+        )
+        app.add_route("/", text_view)
+
+        environ["HTTP_ACCEPT_ENCODING"] = "gzip"
+        environ["HTTP_USER_AGENT"] = "hi"
+        environ["REMOTE_ADDR"] = "/"
+        environ["REQUEST_METHOD"] = "GET"
+        assert str(app(environ, start_response)[0]).startswith("b'\\x1f\\x8b\\x08")
+        assert "content-encoding" in start_response.get_headers()
+
+    def test_not_enabled_on_error_response(self):
+        app, environ, start_response = setup(
+            **self.middleware,
+            gzip_minimum_response_length=1,
+        )
+        app.add_route("/", unauthorized_view)
+
+        environ["HTTP_ACCEPT_ENCODING"] = "gzip"
+        environ["HTTP_USER_AGENT"] = "hi"
+        environ["REMOTE_ADDR"] = "/"
+        environ["REQUEST_METHOD"] = "GET"
+        assert app(environ, start_response) == [bytes("Unauthorized", DEFAULT_ENCODING)]
+        assert "content-encoding" not in start_response.get_headers()
+
+    def test_not_enabled_on_bytes_response(self):
+        app, environ, start_response = setup(
+            **self.middleware,
+            gzip_minimum_response_length=1,
+        )
+        # send a file that's already in bytes form
+        app.add_route("/", file_view)
+
+        environ["HTTP_ACCEPT_ENCODING"] = "gzip"
+        environ["HTTP_USER_AGENT"] = "hi"
+        environ["REMOTE_ADDR"] = "/"
+        environ["REQUEST_METHOD"] = "GET"
+        assert app(environ, start_response) == [bytes("hi", DEFAULT_ENCODING)]
+        assert "content-encoding" not in start_response.get_headers()
+
+
 class TestCorsMiddleware:
     # adapted from:
     # https://github.com/adamchainz/django-cors-headers/blob/main/tests/test_middleware.py
diff --git a/spiderweb/tests/views_for_tests.py b/spiderweb/tests/views_for_tests.py
index 3ae8990..dd8b0a3 100644
--- a/spiderweb/tests/views_for_tests.py
+++ b/spiderweb/tests/views_for_tests.py
@@ -1,7 +1,6 @@
 from spiderweb import HttpResponse
 from spiderweb.decorators import csrf_exempt
-from spiderweb.response import JsonResponse, TemplateResponse
-
+from spiderweb.response import JsonResponse, TemplateResponse, FileResponse
 
 EXAMPLE_HTML_FORM = """
 <form action="" method="post">
@@ -47,3 +46,7 @@ def text_view(request):
 
 def unauthorized_view(request):
     return HttpResponse("Unauthorized", status_code=401)
+
+
+def file_view(request):
+    return FileResponse("spiderweb/tests/staticfiles/file_for_testing_fileresponse.txt")