title: Unit Tests not discovered and executed in Visual Studio 2017 when legacy test settings specified
body: <p>I'm using Visual Studio 2017 Professional 15.4.5 and I found out unit tests will not be discovered when legacy <code>.testsettings</code> is loaded via selecting it in the <code>Test &gt; Test Settings &gt; Select Test Settings</code> menu</p>
  
  <p>Here are steps to reproduce it:</p>
  
  <ol>
  <li>Create a new Solution</li>
  <li><p>Create a <code>Class Library</code> project with target framework <code>.NET Framework 4.5.2</code> with following simple class:</p>
  
  <pre><code>public class Class1
  {
      public bool True =&gt; true;
  }
  </code></pre></li>
  <li><p>Create a <code>Unit Test Project(.Net Framework)</code> with target framework <code>.NET Framework 4.5.2</code> and setup project reference and write a simple test:</p>
  
  <pre><code>[TestClass]
  public class UnitTest1
  {
      [TestMethod]
      public void TestMethod1()
      {
          Assert.IsTrue(new Class1().True);
      }
  }
  </code></pre></li>
  <li><p>Run the test, the test should be discovered and run</p></li>
  <li>Use solution context menu to select <code>Add &gt; New Item</code>, select <code>Test Settings</code> in the left pane and select <code>Test Settings</code> in the middle to create a new test settings.</li>
  <li>Skip the setting by just closing the dialog. Set the test settings by clicking the menu <code>Test &gt; Test Settings &gt; Select Test Settings</code> </li>
  <li>Run the test again, it was not executed and some information can be seen in the Output pane:</li>
  </ol>
  
  <blockquote>
    <p>[2017/12/08 13:36:20 Informational] ------ Run test started ------</p>
    
    <p>[2017/12/08 13:36:22 Warning] Warning : A testsettings file or a runsettings with a ForcedLegacyMode set to true is not supported with the MSTest V2 Adapter.</p>
    
    <p>[2017/12/08 13:36:22 Error] Test adapter sent back a result for an unknown test case. Ignoring result for 'TestMethod1'.</p>
    
    <p>[2017/12/08 13:36:22 Informational] ========== Run test finished: 0 run (0:00:01.9851985) ==========</p>
  </blockquote>
  
  <h2>Updates</h2>
  
  <p>To answer @aruna I followed my own instructions again with VS2017 Professional 15.5.7</p>
  
  <p>The test still failed to run but the output is different:</p>
  
  <blockquote>
    <p>[2018/03/01 13:39:13 Informational] ------ Load Playlist started ------</p>
    
    <p>[2018/03/01 13:39:13 Informational] ========== Load Playlist finished (0:00:00.001) ==========</p>
    
    <p>[2018/03/01 13:40:46 Informational] ------ Discover test started ------</p>
    
    <p>[2018/03/01 13:40:48 Informational] ========== Discover test finished: 1 found (0:00:02.1855628) ==========</p>
    
    <p>[2018/03/01 13:40:48 Informational] ------ Run test started ------</p>
    
    <p>[2018/03/01 13:40:49 Informational] ========== Run test finished: 1 run (0:00:01.5406918) ==========</p>
    
    <p>[2018/03/01 13:41:32 Informational] ------ Run test started ------</p>
    
    <p>[2018/03/01 13:41:34 Warning] Warning : A testsettings file or a runsettings with a ForcedLegacyMode set to true is not supported with the MSTest V2 Adapter.</p>
    
    <p>[2018/03/01 13:41:34 Warning] No test is available in D:\git\demo\unit-test-legacy-settings\UnitTestProject1\bin\Debug\UnitTestProject1.dll. Make sure that test discoverer &amp; executors are registered and platform &amp; framework version settings are appropriate and try again.</p>
    
    <p>[2018/03/01 13:41:34 Informational] ========== Run test finished: 0 run (0:00:02.0727927) ==========</p>
  </blockquote>