test: add reflection test for internal API

Assets/Tests/Editor/Coffee.UIEffect.EditorTests.asmdef

@@ -0,0 +1,12 @@
+{
+    "name": "Coffee.UIEffect.EditorTests",
+    "references": [
+        "Coffee.UIEffect"
+    ],
+    "optionalUnityReferences": [
+        "TestAssemblies"
+    ],
+    "includePlatforms": [
+        "Editor"
+    ]
+}

Assets/Tests/Editor/ReflectionTests.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Reflection;
+using NUnit.Framework;
+using UnityEditor;
+
+public class ReflectionTests
+{
+    [Test]
+    public void ShaderVariantCollectionInspector_DrawShaderEntry()
+    {
+        var type = Type.GetType("UnityEditor.ShaderVariantCollectionInspector, UnityEditor");
+        Assert.IsNotNull(type, "'UnityEditor.ShaderVariantCollectionInspector, UnityEditor' is not found");
+
+        var miDrawShaderEntry = type.GetMethod("DrawShaderEntry", BindingFlags.NonPublic | BindingFlags.Instance);
+        Assert.IsNotNull(miDrawShaderEntry);
+
+        var parameters = miDrawShaderEntry.GetParameters();
+        Assert.AreEqual(1, parameters.Length);
+        Assert.AreEqual(typeof(int), parameters[0].ParameterType);
+    }
+
+    [Test]
+    public void SerializedProperty_gradientValue()
+    {
+        var piGradient = typeof(SerializedProperty)
+            .GetProperty("gradientValue", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
+        Assert.IsNotNull(piGradient);
+
+        Assert.IsTrue(piGradient.CanRead);
+        Assert.IsTrue(piGradient.CanWrite);
+    }
+}