fix: Changes requested

- Added `IValidatableObject` to `CsvWriterSettings`.
- Updated Culture to accept both `Invariant`/`Current` and `InvariantCulture`/`CurrentCulture`.
- Specified only the latter in README.
- Added unit testing for `CsvWriterSettings`.

Extensions/Csv/Cosmos.DataTransfer.CsvExtension.UnitTests/CsvWriterSettingsTests.cs

@@ -0,0 +1,106 @@
+using System.Globalization;
+using Cosmos.DataTransfer.JsonExtension.UnitTests;
+using Microsoft.Extensions.Logging.Abstractions;
+using System.ComponentModel.DataAnnotations;
+using Cosmos.DataTransfer.CsvExtension.Settings;
+using Cosmos.DataTransfer.Interfaces;
+using Cosmos.DataTransfer.JsonExtension;
+
+namespace Cosmos.DataTransfer.CsvExtension.UnitTests;
+
+[TestClass]
+public class CsvWriterSettingsTests
+{
+
+
+    [TestMethod]
+    public void TestDefault(string culture) {
+        var settings = new CsvWriterSettings() { };
+
+        Assert.AreEqual(settings.GetCultureInfo(), CultureInfo.InvariantCulture);        
+        Assert.AreEqual(settings.Validate(new ValidationContext(this)).Count(), 0);
+    }
+
+    [TestMethod]
+    [DataRow("invariant")]
+    [DataRow("Invariant")]
+    [DataRow("invariantCulture")]
+    [DataRow("invariantculture")]
+    public void TestInvariantCulture(string culture) {
+        var settings = new CsvWriterSettings() {
+            Culture = culture
+        };
+        Assert.AreEqual(settings.GetCultureInfo(), CultureInfo.InvariantCulture);        
+        Assert.AreEqual(settings.Validate(new ValidationContext(this)).Count(), 0);
+    }
+
+    [TestMethod]
+    [DataRow("current")]
+    [DataRow("Current")]
+    [DataRow("currentCultuRE")]
+    [DataRow("currentCulture")]
+    public void TestCurrentCulture(string culture) {
+        var settings = new CsvWriterSettings() {
+            Culture = culture
+        };
+        Assert.AreEqual(settings.GetCultureInfo(), CultureInfo.CurrentCulture);
+        Assert.AreEqual(settings.Validate(new ValidationContext(this)).Count(), 0);
+    }
+
+    [TestMethod]
+    public void TestCurrentCultureByName() {
+        var settings = new CsvWriterSettings() {
+            Culture = CultureInfo.CurrentCulture.Name
+        };
+        Assert.AreEqual(settings.GetCultureInfo(), CultureInfo.CurrentCulture);
+        Assert.AreEqual(settings.Validate(new ValidationContext(this)).Count(), 0);
+    }
+
+    [TestMethod]
+    public void TestCultureFails() {
+        var settings = new CsvWriterSettings() {
+            Culture = "not a culture"
+        };
+        var results = settings.Validate(new ValidationContext(this));
+        Assert.AreEqual(results.Count(), 1);
+        Assert.AreEqual(results.First().ErrorMessage, "Could not find CultureInfo `not a culture` on this system.");
+    }
+
+    [TestMethod]
+    [DataRow(null)]
+    [DataRow("")]
+    public void TestCultureMissing(string culture) {
+        var settings = new CsvWriterSettings() {
+            Culture = culture
+        };
+        var results = settings.Validate(new ValidationContext(this));
+        Assert.AreEqual(results.Count(), 1);
+        Assert.AreEqual(results.First().ErrorMessage, "Culture missing.");
+    }
+
+    [TestMethod]
+    public async Task TestDanishCulture() {
+        var outputFile = Path.GetTempFileName();
+        var config = TestHelpers.CreateConfig(new Dictionary<string, string>
+            {
+                { "FilePath", outputFile },
+                { "IncludeHeader", "false" },
+                { "Culture", "da-DK" },
+                { "Delimiter", ";" }
+            });
+
+        var data = new List<DictionaryDataItem>
+        {
+            new(new Dictionary<string, object?>
+            {
+                { "Value", 1.2 }
+            })
+        };
+
+        var sink = new CsvFileSink();
+
+        await sink.WriteAsync(data.ToAsyncEnumerable(), config, new JsonFileSource(), NullLogger.Instance);
+        var result = await File.ReadAllTextAsync(outputFile);
+        Assert.AreEqual(result, "1,2");
+    }
+}

Extensions/Csv/Cosmos.DataTransfer.CsvExtension/Settings/CsvWriterSettings.cs

@@ -1,19 +1,47 @@
 using System.Globalization;
 using Cosmos.DataTransfer.Interfaces;
+using System.ComponentModel.DataAnnotations;
 
 namespace Cosmos.DataTransfer.CsvExtension.Settings;
 
-public class CsvWriterSettings : IDataExtensionSettings
+public class CsvWriterSettings : IDataExtensionSettings, IValidatableObject
 {
     public bool IncludeHeader { get; set; } = true;
     public string Delimiter { get; set; } = ",";
     public string Culture { get; set; } = "InvariantCulture";
     public CultureInfo GetCultureInfo() {
-        switch (this.Culture.ToLower())
+        switch (this.Culture?.ToLower())
         {
-            case "invariantculture": return CultureInfo.InvariantCulture;
-            case "current": return CultureInfo.CurrentCulture;
-            default: return CultureInfo.GetCultureInfo(this.Culture);
+            case "invariant":
+            case "invariantculture": 
+                return CultureInfo.InvariantCulture;
+            case "current": 
+            case "currentculture":
+                return CultureInfo.CurrentCulture;
+            default: return CultureInfo.GetCultureInfo(this.Culture!);
+        }
+    }
+
+    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
+    {
+        ValidationResult? result = null; 
+        try {
+            _ = this.GetCultureInfo();
+        } catch (CultureNotFoundException) {
+            result = new ValidationResult(
+                $"Could not find CultureInfo `{this.Culture}` on this system.",
+                new string[] { "Culture" }
+            );
+        } catch (ArgumentNullException) {
+            result = new ValidationResult(
+                $"Culture missing.",
+                new string[] { "Culture" }
+            );
+        }
+
+
+        if (result != null) {
+            yield return result;
         }
     }
 }

Extensions/Csv/README.md

@@ -36,12 +36,14 @@ Source supports an optional `Delimiter` parameter (`,` by default) and an option
 
 Sink supports an optional `Delimiter` parameter (`,` by default) and an optional `IncludeHeader` parameter (`true` by default) to add a leading row of column names.
 
-Formatting options, or locale, can be set with an optional `Culture` setting (`"Invariant"` by default). 
+Formatting options, or locale, can be set with an optional `Culture` setting (`"InvariantCulture"` by default). 
 This specifies how e.g., numbers and dates are formatted according to a specific culture. 
-Set to `"Current"` to use the system's or process' current locale setting 
+Set to `"InvariantCulture"` to use the system's or process' current locale setting 
 (see [CultureInfo.CurrentCulture](https://learn.microsoft.com/en-us/dotnet/api/system.globalization.cultureinfo.currentculture)),
 or e.g., `"en"`, `"en-GB"`, or `"en-US"` for English standards (period, `.`, as decimal separator and other regional standards), 
 "da-DK" for Danish (comma, `,`, as decimal separator), etc.
+Note, if using a culture with comma as decimal separator, specify a different delimiter (e.g., semi-colon, `;`), else all numbers
+will be written enclosed with quotes.
 
 ```json
 {