Add tests for Tin grader

tin/apps/assignments/tests/test_grader.py

@@ -0,0 +1,50 @@
+from __future__ import annotations
+
+import io
+
+from django.conf import settings
+from django.urls import reverse
+
+from tin.tests import is_redirect, login, str_to_html
+
+
+@login("teacher")
+def test_grader_view(client, assignment):
+    sample_grader = io.BytesIO(b"some text")
+    response = client.post(
+        reverse("assignments:manage_grader", args=[assignment.id]), {"grader_file": sample_grader}
+    )
+
+    assert is_redirect(response)
+
+
+@login("teacher")
+def test_incorrect_grader(client, assignment):
+    binary_data = io.BytesIO(b"b" * (settings.SUBMISSION_SIZE_LIMIT + 1))
+    response = client.post(
+        reverse("assignments:manage_grader", args=[assignment.id]), {"grader_file": binary_data}
+    )
+
+    error = str_to_html(
+        "That file's too large. Are you sure it's a Python program?",
+    )
+    assert error in response.content.decode("utf-8")
+
+
+@login("teacher")
+def test_download_grader(client, assignment):
+    response = client.post(
+        reverse("assignments:download_grader", args=[assignment.id]),
+    )
+    assert response.status_code == 404
+
+    code = "print('hello, world')"
+    assignment.save_grader_file(code)
+    assignment.save()
+
+    response = client.post(
+        reverse("assignments:download_grader", args=[assignment.id]),
+    )
+
+    assert response.status_code == 200
+    assert response.content.decode("utf-8") == code