Add IDictionary type converter

Add a new type converter for IDictionary types which unwraps PScustomObjects
before serializing.

Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>

Author: gabriel-samfira

Tests/powershell-yaml.Tests.ps1

@@ -29,7 +29,7 @@ InModuleScope $moduleName {
     $compareStrictly = Get-EquivalencyOption -Comparator Equality
 
     Describe "Test PSCustomObject wrapped values are serialized correctly" {
-        Context "Wrapped values" {
+        Context "A PSCustomObject containing nested PSCustomObjects" {
             It "Should serialize correctly" {
                 $expectBigInt = [System.Numerics.BigInteger]::Parse("9999999999999999999999999999999999999999999999999")
                 $obj = [PSCustomObject]@{a = Write-Output 'string'; b = Write-Output 1; c = Write-Output @{nested = $true};d = [pscustomobject]$expectBigInt}
@@ -41,6 +41,37 @@ InModuleScope $moduleName {
                 Assert-Equivalent -Options $compareStrictly -Expected $expectBigInt -Actual $fromYaml["d"]
             }
         }
+
+        Context "A hashtable containing nested PSCustomObjects" {
+            It "Should serialize correctly" {
+                $expectBigInt = [System.Numerics.BigInteger]::Parse("9999999999999999999999999999999999999999999999999")
+                $obj = @{a = Write-Output 'string'; b = Write-Output 1; c = Write-Output @{nested = $true};d = [pscustomobject]$expectBigInt}
+                $asYaml = ConvertTo-Yaml $obj
+                $fromYaml = ConvertFrom-Yaml $asYaml
+
+                Assert-Equivalent -Options $compareStrictly -Expected "string" -Actual $fromYaml["a"]
+                Assert-Equivalent -Options $compareStrictly -Expected 1 -Actual $fromYaml["b"]
+                Assert-Equivalent -Options $compareStrictly -Expected $expectBigInt -Actual $fromYaml["d"]
+            }
+        }
+
+        Context "A generic dictionary containing nested PSCustomObjects" {
+            It "Should serialize correctly" {
+                $expectBigInt = [System.Numerics.BigInteger]::Parse("9999999999999999999999999999999999999999999999999")
+                $obj = [System.Collections.Generic.Dictionary[string, object]]::new()
+                $obj["a"] = Write-Output 'string'
+                $obj["b"] = Write-Output 1
+                $obj["c"] = Write-Output @{nested = $true}
+                $obj["d"] = [pscustomobject]$expectBigInt
+
+                $asYaml = ConvertTo-Yaml $obj
+                $fromYaml = ConvertFrom-Yaml $asYaml
+
+                Assert-Equivalent -Options $compareStrictly -Expected "string" -Actual $fromYaml["a"]
+                Assert-Equivalent -Options $compareStrictly -Expected 1 -Actual $fromYaml["b"]
+                Assert-Equivalent -Options $compareStrictly -Expected $expectBigInt -Actual $fromYaml["d"]
+            }
+        }
     }
 
     Describe "Test encode-decode symmetry." {

lib/net47/PowerShellYamlSerializer.dll

@@ -49,6 +49,46 @@ public void WriteYaml(IEmitter emitter, object value, Type type, ObjectSerialize
     }
 }
 
+public class IDictionaryTypeConverter :  IYamlTypeConverter {
+
+    private bool omitNullValues;
+
+    public IDictionaryTypeConverter(bool omitNullValues = false) {
+        this.omitNullValues = omitNullValues;
+    }
+
+    public bool Accepts(Type type) {
+        return typeof(IDictionary).IsAssignableFrom(type);
+    }
+
+    public object ReadYaml(IParser parser, Type type, ObjectDeserializer rootDeserializer) {
+        var deserializedObject = rootDeserializer(typeof(IDictionary<string, object>)) as IDictionary;
+        return deserializedObject;
+    }
+
+    public void WriteYaml(IEmitter emitter, object value, Type type, ObjectSerializer serializer) {
+        var hObj = (IDictionary)value;
+        emitter.Emit(new MappingStart());
+        foreach (DictionaryEntry entry in hObj) {
+            if(entry.Value == null) {
+                if (this.omitNullValues == true) {
+                    continue;
+                }
+                serializer(entry.Key, entry.Key.GetType());
+                emitter.Emit(new Scalar(AnchorName.Empty, "tag:yaml.org,2002:null", "", ScalarStyle.Plain, true, false));
+                continue;
+            }
+            serializer(entry.Key, entry.Key.GetType());
+            if (entry.Value is PSObject nestedObj) {
+                serializer(nestedObj.BaseObject, nestedObj.BaseObject.GetType());
+            } else {
+                serializer(entry.Value, entry.Value.GetType());
+            }
+        }
+        emitter.Emit(new MappingEnd());
+    }
+}
+
 public class PSObjectTypeConverter : IYamlTypeConverter {
 
     private bool omitNullValues;
@@ -70,7 +110,6 @@ public object ReadYaml(IParser parser, Type type, ObjectDeserializer rootDeseria
 
     public void WriteYaml(IEmitter emitter, object value, Type type, ObjectSerializer serializer) {
         var psObj = (PSObject)value;
-
         emitter.Emit(new MappingStart());
         foreach (var prop in psObj.Properties) {
             if (prop.Value == null) {
@@ -161,6 +200,7 @@ public static SerializerBuilder BuildSerializer(
         builder = builder
             .WithEventEmitter(next => new StringQuotingEmitter(next))
             .WithTypeConverter(new BigIntegerTypeConverter())
+            .WithTypeConverter(new IDictionaryTypeConverter(omitNullValues))
             .WithTypeConverter(new PSObjectTypeConverter(omitNullValues));
         if (omitNullValues == true) {
             builder = builder