Add a check that the custom JSON report metadata is always JSON serializable

Otherwise it just shows up as a warning in the test results, which might
easily be missed.

Author: asmeurer

reporting.py

@@ -4,6 +4,7 @@
 
 from types import BuiltinFunctionType, FunctionType
 import dataclasses
+import json
 
 from hypothesis.strategies import SearchStrategy
 
@@ -42,6 +43,13 @@ def add_api_name_to_metadata(request, json_metadata):
     """
     Additional per-test metadata for --json-report
     """
+    def add_metadata(name, obj):
+        obj = to_json_serializable(obj)
+        # Ensure everything is JSON serializable. If this errors, it means the
+        # given type needs to be added to to_json_serializable above.
+        json.dumps(obj)
+        json_metadata[name] = obj
+
     test_module = request.module.__name__
     if test_module.startswith('array_api_tests.meta'):
         return
@@ -54,20 +62,20 @@ def add_api_name_to_metadata(request, json_metadata):
     else:
         array_api_function_name = test_function[len('test_'):]
 
-    json_metadata['test_module'] = test_module
-    json_metadata['test_function'] = test_function
-    json_metadata['array_api_function_name'] = array_api_function_name
+    add_metadata('test_module', test_module)
+    add_metadata('test_function', test_function)
+    add_metadata('array_api_function_name', array_api_function_name)
 
     if hasattr(request.node, 'callspec'):
         params = request.node.callspec.params
-        json_metadata['params'] = to_json_serializable(params)
+        add_metadata('params', params)
 
     def finalizer():
         # TODO: This metadata is all in the form of error strings. It might be
         # nice to extract the hypothesis failing inputs directly somehow.
         if hasattr(request.node, 'hypothesis_report_information'):
-            json_metadata['hypothesis_report_information'] = request.node.hypothesis_report_information
+            add_metadata('hypothesis_report_information', request.node.hypothesis_report_information)
         if hasattr(request.node, 'hypothesis_statistics'):
-            json_metadata['hypothesis_statistics'] = request.node.hypothesis_statistics
+            add_metadata('hypothesis_statistics', request.node.hypothesis_statistics)
 
     request.addfinalizer(finalizer)