Add tests to test-project

test-project/Assets/Tests/EditMode/EditModeTests.asmdef

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+{
+    "name": "EditModeTests",
+    "references": [
+        "UnityEngine.TestRunner",
+        "UnityEditor.TestRunner",
+        "MyScripts"
+    ],
+    "includePlatforms": [
+        "Editor"
+    ],
+    "excludePlatforms": [],
+    "allowUnsafeCode": false,
+    "overrideReferences": true,
+    "precompiledReferences": [
+        "nunit.framework.dll"
+    ],
+    "autoReferenced": false,
+    "defineConstraints": [
+        "UNITY_INCLUDE_TESTS"
+    ],
+    "versionDefines": []
+}

test-project/Assets/Tests/EditMode/EditModeTests.asmdef.meta

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+guid: 3d1ca36213121e342ae81b3126b7bead
+AssemblyDefinitionImporter:
+  externalObjects: {}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

test-project/Assets/Tests/EditMode/SampleEditModeTest.cs

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+using System.Collections;
+using System.Collections.Generic;
+using NUnit.Framework;
+using UnityEngine;
+using UnityEngine.TestTools;
+
+namespace Tests
+{
+  public class SampleEditModeTest
+  {
+    [Test]
+    public void TestIncrement()
+    {
+      // Given
+      var counter = new BasicCounter(0);
+
+      // When
+      counter.Increment();
+
+      // Then
+      Assert.AreEqual(1, counter.Count);
+    }
+
+    [Test]
+    public void TestMaxCount()
+    {
+      // Given
+      var counter = new BasicCounter(BasicCounter.MaxCount);
+
+      // When
+      counter.Increment();
+
+      // Then
+      Assert.AreEqual(BasicCounter.MaxCount, counter.Count);
+    }
+
+  }
+}

test-project/Assets/Tests/EditMode/SampleEditModeTest.cs.meta

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+fileFormatVersion: 2
+guid: 78190067de361bb49b5d840b63eb93fc
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData:
+  assetBundleName:
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