use better format for float (#806)

methane · web-flow · commit 18b0bcb9bf05 · 2019-09-21T18:16:35.000+09:00
diff --git a/pymysql/converters.py b/pymysql/converters.py
@@ -54,7 +54,12 @@ def escape_int(value, mapping=None):
     return str(value)
 
 def escape_float(value, mapping=None):
-    return ('%.15g' % value)
+    s = repr(value)
+    if s in ('inf', 'nan'):
+        raise ProgrammingError("%s can not be used with MySQL" % s)
+    if 'e' not in s:
+        s += 'e0'
+    return s
 
 _escape_table = [unichr(x) for x in range(128)]
 _escape_table[0] = u'\\0'
diff --git a/pymysql/tests/thirdparty/test_MySQLdb/test_MySQLdb_capabilities.py b/pymysql/tests/thirdparty/test_MySQLdb/test_MySQLdb_capabilities.py
@@ -90,7 +90,7 @@ def test_literal_int(self):
         self.assertTrue("2" == self.connection.literal(2))
 
     def test_literal_float(self):
-        self.assertTrue("3.1415" == self.connection.literal(3.1415))
+        self.assertEqual("3.1415e0", self.connection.literal(3.1415))
 
     def test_literal_string(self):
         self.assertTrue("'foo'" == self.connection.literal("foo"))
