diff --git a/X10D.Tests/src/Collections/DictionaryTests.cs b/X10D.Tests/src/Collections/DictionaryTests.cs
index 9fb8be2..907b1f9 100644
--- a/X10D.Tests/src/Collections/DictionaryTests.cs
+++ b/X10D.Tests/src/Collections/DictionaryTests.cs
@@ -7,7 +7,7 @@ namespace X10D.Tests.Collections;
 public class DictionaryTests
 {
     [TestMethod]
-    public void AddOrUpdate_ShouldAddNewKey_IfNotExists()
+    public void AddOrUpdate_ShouldAddNewKey_IfNotExists_GivenConcreteDictionary()
     {
         var dictionary = new Dictionary<int, string>();
         Assert.IsFalse(dictionary.ContainsKey(1));
@@ -32,7 +32,32 @@ public class DictionaryTests
     }
 
     [TestMethod]
-    public void AddOrUpdate_ShouldUpdateKey_IfExists()
+    public void AddOrUpdate_ShouldAddNewKey_IfNotExists_GivenIDictionary()
+    {
+        IDictionary<int, string> dictionary = new Dictionary<int, string>();
+        Assert.IsFalse(dictionary.ContainsKey(1));
+
+        dictionary.AddOrUpdate(1, "one", (_, _) => string.Empty);
+        Assert.IsTrue(dictionary.ContainsKey(1));
+        Assert.AreEqual("one", dictionary[1]);
+
+        dictionary.Clear();
+        Assert.IsFalse(dictionary.ContainsKey(1));
+
+        dictionary.AddOrUpdate(1, _ => "one", (_, _) => string.Empty);
+        Assert.IsTrue(dictionary.ContainsKey(1));
+        Assert.AreEqual("one", dictionary[1]);
+
+        dictionary.Clear();
+        Assert.IsFalse(dictionary.ContainsKey(1));
+
+        dictionary.AddOrUpdate(1, (_, _) => "one", (_, _, _) => string.Empty, 0);
+        Assert.IsTrue(dictionary.ContainsKey(1));
+        Assert.AreEqual("one", dictionary[1]);
+    }
+
+    [TestMethod]
+    public void AddOrUpdate_ShouldUpdateKey_IfExists_GivenConcreteDirection()
     {
         var dictionary = new Dictionary<int, string> {[1] = "one"};
         Assert.IsTrue(dictionary.ContainsKey(1));
@@ -60,7 +85,35 @@ public class DictionaryTests
     }
 
     [TestMethod]
-    public void AddOrUpdate_ShouldThrow_GivenNullDictionary()
+    public void AddOrUpdate_ShouldUpdateKey_IfExists_GivenIDictionary()
+    {
+        IDictionary<int, string> dictionary = new Dictionary<int, string> {[1] = "one"};
+        Assert.IsTrue(dictionary.ContainsKey(1));
+        Assert.AreEqual("one", dictionary[1]);
+
+        dictionary.AddOrUpdate(1, string.Empty, (_, _) => "two");
+        Assert.IsTrue(dictionary.ContainsKey(1));
+        Assert.AreEqual("two", dictionary[1]);
+
+        dictionary.Clear();
+        Assert.IsFalse(dictionary.ContainsKey(1));
+        dictionary[1] = "one";
+
+        dictionary.AddOrUpdate(1, _ => string.Empty, (_, _) => "two");
+        Assert.IsTrue(dictionary.ContainsKey(1));
+        Assert.AreEqual("two", dictionary[1]);
+
+        dictionary.Clear();
+        Assert.IsFalse(dictionary.ContainsKey(1));
+        dictionary[1] = "one";
+
+        dictionary.AddOrUpdate(1, (_, _) => string.Empty, (_, _, _) => "two", 0);
+        Assert.IsTrue(dictionary.ContainsKey(1));
+        Assert.AreEqual("two", dictionary[1]);
+    }
+
+    [TestMethod]
+    public void AddOrUpdate_ShouldThrow_GivenNullDictionary_GivenConcreteDictionary()
     {
         Dictionary<int, string>? dictionary = null;
         Assert.ThrowsException<ArgumentNullException>(() => dictionary!.AddOrUpdate(1, string.Empty, (_, _) => string.Empty));
@@ -71,7 +124,18 @@ public class DictionaryTests
     }
 
     [TestMethod]
-    public void AddOrUpdate_ShouldThrow_GivenNullUpdateValueFactory()
+    public void AddOrUpdate_ShouldThrow_GivenNullDictionary_GivenIDictionary()
+    {
+        IDictionary<int, string>? dictionary = null;
+        Assert.ThrowsException<ArgumentNullException>(() => dictionary!.AddOrUpdate(1, string.Empty, (_, _) => string.Empty));
+        Assert.ThrowsException<ArgumentNullException>(() =>
+            dictionary!.AddOrUpdate(1, _ => string.Empty, (_, _) => string.Empty));
+        Assert.ThrowsException<ArgumentNullException>(() =>
+            dictionary!.AddOrUpdate(1, (_, _) => string.Empty, (_, _, _) => string.Empty, 0));
+    }
+
+    [TestMethod]
+    public void AddOrUpdate_ShouldThrow_GivenNullUpdateValueFactory_GivenConcreteDictionary()
     {
         var dictionary = new Dictionary<int, string>();
         Assert.ThrowsException<ArgumentNullException>(() => dictionary.AddOrUpdate(1, string.Empty, null!));
@@ -80,7 +144,16 @@ public class DictionaryTests
     }
 
     [TestMethod]
-    public void AddOrUpdate_ShouldThrow_GivenNullAddValueFactory()
+    public void AddOrUpdate_ShouldThrow_GivenNullUpdateValueFactory_GivenIDictionary()
+    {
+        IDictionary<int, string> dictionary = new Dictionary<int, string>();
+        Assert.ThrowsException<ArgumentNullException>(() => dictionary.AddOrUpdate(1, string.Empty, null!));
+        Assert.ThrowsException<ArgumentNullException>(() => dictionary.AddOrUpdate(1, _ => string.Empty, null!));
+        Assert.ThrowsException<ArgumentNullException>(() => dictionary.AddOrUpdate(1, (_, _) => string.Empty, null!, 0));
+    }
+
+    [TestMethod]
+    public void AddOrUpdate_ShouldThrow_GivenNullAddValueFactory_GivenConcreteDictionary()
     {
         var dictionary = new Dictionary<int, string>();
         Func<int, string>? addValueFactory = null;
@@ -88,6 +161,15 @@ public class DictionaryTests
         Assert.ThrowsException<ArgumentNullException>(() => dictionary.AddOrUpdate(1, null!, (_, _, _) => "one", 0));
     }
 
+    [TestMethod]
+    public void AddOrUpdate_ShouldThrow_GivenNullAddValueFactory_GivenIDictionary()
+    {
+        IDictionary<int, string> dictionary = new Dictionary<int, string>();
+        Func<int, string>? addValueFactory = null;
+        Assert.ThrowsException<ArgumentNullException>(() => dictionary.AddOrUpdate(1, addValueFactory!, (_, _) => "one"));
+        Assert.ThrowsException<ArgumentNullException>(() => dictionary.AddOrUpdate(1, null!, (_, _, _) => "one", 0));
+    }
+
     [TestMethod]
     public void ToConnectionString_ShouldReturnConnectionString()
     {