CSHARP-2821: Decimal128.ToDouble() fails if culture is FR

Author: MikalaiMazurenka

src/MongoDB.Bson/ObjectModel/Decimal128.cs

@@ -793,7 +793,7 @@ public static double ToDouble(Decimal128 d)
             {
                 // TODO: implement this more efficiently
                 var stringValue = d.ToString();
-                return double.Parse(stringValue);
+                return double.Parse(stringValue, CultureInfo.InvariantCulture);
             }
             else if (Flags.IsSecondForm(d._highBits))
             {
@@ -945,7 +945,7 @@ public static float ToSingle(Decimal128 d)
             {
                 // TODO: implement this more efficiently
                 var stringValue = d.ToString();
-                return float.Parse(stringValue);
+                return float.Parse(stringValue, CultureInfo.InvariantCulture);
             }
             else if (Flags.IsSecondForm(d._highBits))
             {

tests/MongoDB.Bson.Tests/ObjectModel/Decimal128Tests.cs

@@ -16,6 +16,7 @@
 using System;
 using FluentAssertions;
 using System.Globalization;
+using System.Threading;
 using Xunit;
 
 namespace MongoDB.Bson.Tests
@@ -121,6 +122,46 @@ public void ToDecimal_should_throw_when_value_is_out_of_range(string valueString
             exception.Should().BeOfType<OverflowException>();
         }
 
+        [Theory]
+        [InlineData("123.456", 123.456)]
+        public void ToDouble_should_not_depend_on_current_culture(string valueString, double expectedDouble)
+        {
+            var currentCulture = Thread.CurrentThread.CurrentCulture;
+            try
+            {
+                Thread.CurrentThread.CurrentCulture = new CultureInfo("fr-FR");
+                var subject = Decimal128.Parse(valueString);
+
+                var result = Decimal128.ToDouble(subject);
+
+                result.Should().Be(expectedDouble);
+            }
+            finally
+            {
+                Thread.CurrentThread.CurrentCulture = currentCulture;
+            }
+        }
+
+        [Theory]
+        [InlineData("123.456", 123.456)]
+        public void ToSingle_should_not_depend_on_current_culture(string valueString, float expectedFloat)
+        {
+            var currentCulture = Thread.CurrentThread.CurrentCulture;
+            try
+            {
+                Thread.CurrentThread.CurrentCulture = new CultureInfo("fr-FR");
+                var subject = Decimal128.Parse(valueString);
+
+                var result = Decimal128.ToSingle(subject);
+
+                result.Should().Be(expectedFloat);
+            }
+            finally
+            {
+                Thread.CurrentThread.CurrentCulture = currentCulture;
+            }
+        }
+
         [Theory]
         [InlineData((byte)0, "0")]
         [InlineData((byte)1, "1")]