test(configuration): add coverage for nested override merge behavior

Author: arturcic

src/GitVersion.Configuration.Tests/Configuration/ConfigurationHelperTests.cs

@@ -0,0 +1,82 @@
+namespace GitVersion.Configuration.Tests;
+
+[TestFixture]
+public class ConfigurationHelperTests
+{
+    [Test]
+    public void Override_Replaces_Nested_Dictionary_With_Scalar_Value()
+    {
+        Dictionary<object, object?> original =
+            new()
+            {
+                ["key"] = new Dictionary<object, object?> { ["nested"] = "value" }
+            };
+        var helper = new ConfigurationHelper(original);
+
+        IReadOnlyDictionary<object, object?> source =
+            new Dictionary<object, object?>
+            {
+                ["key"] = "override"
+            };
+
+        helper.Override(source);
+
+        helper.Dictionary["key"].ShouldBe("override");
+    }
+
+    [Test]
+    public void Override_Merges_Nested_Dictionaries_Recursively()
+    {
+        Dictionary<object, object?> original =
+            new()
+            {
+                ["key"] = new Dictionary<object, object?>
+                {
+                    ["a"] = 1,
+                    ["b"] = 2
+                }
+            };
+        var helper = new ConfigurationHelper(original);
+
+        IReadOnlyDictionary<object, object?> source =
+            new Dictionary<object, object?>
+            {
+                ["key"] = new Dictionary<object, object?>
+                {
+                    ["b"] = 3,
+                    ["c"] = 4
+                }
+            };
+
+        helper.Override(source);
+
+        var nested = (IDictionary<object, object?>)helper.Dictionary["key"]!;
+        nested["a"].ShouldBe(1);
+        nested["b"].ShouldBe(3);
+        nested["c"].ShouldBe(4);
+    }
+
+    [Test]
+    public void Override_Clones_New_Nested_Dictionaries()
+    {
+        Dictionary<object, object?> original = [];
+        var helper = new ConfigurationHelper(original);
+
+        Dictionary<object, object?> sourceNested =
+            new()
+            {
+                ["a"] = 1
+            };
+        IReadOnlyDictionary<object, object?> source =
+            new Dictionary<object, object?>
+            {
+                ["key"] = sourceNested
+            };
+
+        helper.Override(source);
+        sourceNested["a"] = 2;
+
+        var nested = (IDictionary<object, object?>)helper.Dictionary["key"]!;
+        nested["a"].ShouldBe(1);
+    }
+}