test: subclass vcr.cassette.Cassette to handle identical requests with different responses

Thanks to @vickyliin for suggesting this workaround for
kevin1024/vcrpy#753.

Author: cfm

client/tests/sdk/utils.py

@@ -12,6 +12,24 @@
 VCR = vcr.VCR(cassette_library_dir="tests/sdk/data/")
 
 
+class Cassette(vcr.cassette.Cassette):
+    """Subclass `Cassette` to be able to handle two or more identical requests
+    with different responses at different positions in the cassette.  Thanks to
+    @vickyliin for suggesting this workaround for kevin1024/vcrpy#753."""
+
+    def append_and_play(self, request, response) -> None:
+        prev_len_data = len(self.data)
+        super().append(request, response)
+        is_appended = len(self.data) == prev_len_data + 1
+        if is_appended:
+            self.play_counts[prev_len_data] += 1
+
+    def _load(self) -> None:
+        super()._load()
+        self.append = self.append_and_play
+        self._load = None
+
+
 class VCRAPI(API):
     """Subclass `API` so that `_send_json_request()` is instrumented to record
     and replay VCR.py cassettes.
@@ -52,7 +70,12 @@ def use_cassette(func):
         def wrapper(self, *args, **kwargs):
             # We have to specify an explicit path for each cassette because
             # we're not using vcr.use_cassette() directly as a decorator.
-            with VCR.use_cassette(f"{func.__name__}.yaml") as cassette:
+            context = VCR.use_cassette(f"{func.__name__}.yaml")
+
+            # Override `Cassette` to use our subclass before we enter the
+            # context manager.
+            context.cls = Cassette
+            with context as cassette:
                 with patch.object(VCRAPI, "_cassette", cassette, create=True):
                     return func(self, *args, **kwargs)