Use invariant culture when converting float constant to string (#245)

* Use invariant culture when converting float constant to string

* Fix formatting

* Use number in thousands + fraction (distance to moon in km)

Author: atifaziz

src/CSnakes.SourceGeneration/Parser/Types/PythonConstant.cs

@@ -1,4 +1,6 @@
-namespace CSnakes.Parser.Types;
+using System.Globalization;
+
+namespace CSnakes.Parser.Types;
 
 public abstract class PythonConstant
 {
@@ -23,7 +25,7 @@ public sealed class BinaryInteger(long value) : Integer(value)
     public sealed class Float(double value) : PythonConstant
     {
         public double Value { get; } = value;
-        public override string ToString() => Value.ToString();
+        public override string ToString() => Value.ToString(CultureInfo.InvariantCulture);
     }
 
     public sealed class String(string value) : PythonConstant

src/CSnakes.Tests/PythonConstantTests.cs

@@ -0,0 +1,30 @@
+using CSnakes.Parser.Types;
+using System.Globalization;
+
+namespace CSnakes.Tests;
+public class PythonConstantTests
+{
+    public sealed class FloatTests
+    {
+        [Fact]
+        public void ToString_Is_Not_Culture_Specific()
+        {
+            var testCulture = (CultureInfo)CultureInfo.InvariantCulture.Clone();
+            testCulture.NumberFormat.NumberDecimalSeparator = ",";
+            testCulture.NumberFormat.NumberGroupSeparator = ".";
+
+            var oldCulture = CultureInfo.CurrentCulture;
+            CultureInfo.CurrentCulture = CultureInfo.ReadOnly(testCulture);
+
+            try
+            {
+                var n = new PythonConstant.Float(1_737.4);
+                Assert.Equal("1737.4", n.ToString());
+            }
+            finally
+            {
+                CultureInfo.CurrentCulture = oldCulture;
+            }
+        }
+    }
+}