fix: inserting non-finite floats with insert_rows() (#728)

google/cloud/bigquery/_helpers.py

@@ -17,6 +17,7 @@
 import base64
 import datetime
 import decimal
+import math
 import re
 
 from google.cloud._helpers import UTC
@@ -305,7 +306,12 @@ def _int_to_json(value):
 
 def _float_to_json(value):
     """Coerce 'value' to an JSON-compatible representation."""
-    return value if value is None else float(value)
+    if value is None:
+        return None
+    elif math.isnan(value) or math.isinf(value):
+        return str(value)
+    else:
+        return float(value)
 
 
 def _decimal_to_json(value):

tests/unit/test__helpers.py

@@ -656,9 +656,24 @@ def _call_fut(self, value):
 
         return _float_to_json(value)
 
+    def test_w_none(self):
+        self.assertEqual(self._call_fut(None), None)
+
     def test_w_float(self):
         self.assertEqual(self._call_fut(1.23), 1.23)
 
+    def test_w_nan(self):
+        result = self._call_fut(float("nan"))
+        self.assertEqual(result.lower(), "nan")
+
+    def test_w_infinity(self):
+        result = self._call_fut(float("inf"))
+        self.assertEqual(result.lower(), "inf")
+
+    def test_w_negative_infinity(self):
+        result = self._call_fut(float("-inf"))
+        self.assertEqual(result.lower(), "-inf")
+
 
 class Test_decimal_to_json(unittest.TestCase):
     def _call_fut(self, value):