Correct types passed to content_from_stream

Signed-off-by: Stephen Finucane <stephen@that.guru>

Author: stephenfin

tests/test_testresult.py

@@ -2108,11 +2108,13 @@ def setUp(self):
         self.result = TextTestResult(io.StringIO())
 
     def getvalue(self):
+        assert isinstance(self.result.stream, io.StringIO)
         return self.result.stream.getvalue()
 
     def test__init_sets_stream(self):
-        result = TextTestResult("fp")
-        self.assertEqual("fp", result.stream)
+        stream = io.StringIO()
+        result = TextTestResult(stream)
+        self.assertEqual(stream, result.stream)
 
     def reset_output(self):
         self.result.stream = io.StringIO()
@@ -2285,6 +2287,7 @@ def __init__(self, stream):
 
             def addSuccess(self, test, details=None):
                 super().addSuccess(test, details)
+                assert self.stream is not None
                 self.stream.write("CUSTOM_SUCCESS_MARKER\n")
 
         stream = io.StringIO()
@@ -3562,7 +3565,7 @@ def test_no_details(self):
 
     def test_binary_content(self):
         content = content_from_stream(
-            io.StringIO("foo"), content_type=ContentType("image", "jpeg")
+            io.BytesIO(b"foo"), content_type=ContentType("image", "jpeg")
         )
         string = _details_to_str({"attachment": content})
         self.assertThat(
@@ -3617,16 +3620,16 @@ def test_empty_attachment(self):
         )
 
     def test_lots_of_different_attachments(self):
-        def jpg(x):
-            return content_from_stream(io.StringIO(x), ContentType("image", "jpeg"))
+        def jpg(x: bytes) -> Content:
+            return content_from_stream(io.BytesIO(x), ContentType("image", "jpeg"))
 
         attachments = {
             "attachment": text_content("foo"),
             "attachment-1": text_content("traceback"),
-            "attachment-2": jpg("pic1"),
+            "attachment-2": jpg(b"pic1"),
             "attachment-3": text_content("bar"),
             "attachment-4": text_content(""),
-            "attachment-5": jpg("pic2"),
+            "attachment-5": jpg(b"pic2"),
         }
         string = _details_to_str(attachments, special="attachment-1")
         self.assertThat(