Add print extension method for LanguageExt Errors (#33)

Closes #30

Author: ChristopherMann

src/Dbosoft.Functional.Json/Dbosoft.Functional.Json.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
-	  <Nullable>enable</Nullable>
+    <Nullable>enable</Nullable>
     <PackageId>Dbosoft.Functional.Json</PackageId>
     <Description>JSON support for LanguageExt NewType.</Description>
   </PropertyGroup>

src/Dbosoft.Functional/ErrorExtensions.cs

@@ -0,0 +1,17 @@
+using System;
+using LanguageExt.Common;
+
+namespace Dbosoft.Functional;
+
+#nullable enable
+
+public static class ErrorExtensions
+{
+    public static string Print(this Error error) =>
+        error switch
+        {
+            ManyErrors manyErrors => string.Join(Environment.NewLine, manyErrors.Errors.Map(Print)),
+            Exceptional exceptional => exceptional.ToException().ToString(),
+            _ => error.Message + error.Inner.Map(inner => $"{Environment.NewLine}{Print(inner)}").IfNone(""),
+        };
+}

test/Dbosoft.Functional.Tests/ErrorExtensionsTests.cs

@@ -0,0 +1,62 @@
+using LanguageExt.Common;
+
+namespace Dbosoft.Functional.Tests;
+
+public class ErrorExtensionsTests
+{
+    [Fact]
+    public void Print_ComplexHierarchy_ReturnsString()
+    {
+        Error error;
+        try
+        {
+            throw new Exception("test exception");
+        }
+        catch (Exception ex)
+        {
+            error = Error.New("root error",
+                Error.Many(
+                    Error.New("outer error",
+                        Error.New("inner error")),
+                    Error.New(ex)));
+        }
+
+        var result = error.Print();
+        result.Should().StartWith(
+            """
+            root error
+            outer error
+            inner error
+            System.Exception: test exception
+            """);
+    }
+
+    [Fact]
+    public void Print_NestedException_ReturnsString()
+    {
+        Error error;
+        try
+        {
+            try
+            {
+                throw new Exception("inner exception");
+            }
+            catch (Exception ex)
+            {
+                throw new Exception("outer exception", ex);
+            }
+        }
+        catch (Exception ex)
+        {
+            error = Error.New("root error", Error.New(ex));
+        }
+
+        var result = error.Print(); 
+        result.Should().StartWith(
+            """
+            root error
+            System.Exception: outer exception
+             ---> System.Exception: inner exception
+            """);
+    }
+}