Fix assembly name check

The calculation of assembly name for a project needs to take into
account default when it's a new SDK project.

src/Tools/BuildBoss/ProjectCheckerUtil.cs

@@ -367,6 +367,11 @@ private List<ProjectKey> GetProjectReferencesTransitive(IEnumerable<ProjectKey>
             return list;
         }
 
+        /// <summary>
+        /// Our infrastructure depends on test assembly names having a very specific set of 
+        /// suffixes: UnitTest and IntegrationTests. This check will verify that both test assemblies
+        /// are properly named and non-test assemblies are not incorrectly named.
+        /// </summary>
         private bool IsUnitTestCorrectlySpecified(TextWriter textWriter, RoslynProjectData data)
         {
             if (ProjectType != ProjectFileType.CSharp && ProjectType != ProjectFileType.Basic)
@@ -379,14 +384,22 @@ private bool IsUnitTestCorrectlySpecified(TextWriter textWriter, RoslynProjectDa
                 return true;
             }
 
+            string name = null;
             var element = _projectUtil.FindSingleProperty("AssemblyName");
-            if (element == null)
+            if (element != null)
+            {
+                name = element.Value.Trim();
+            }
+            else if (_projectUtil.IsNewSdk)
+            {
+                name = Path.GetFileNameWithoutExtension(_data.FileName);
+            }
+            else
             {
                 textWriter.WriteLine($"Need to specify AssemblyName");
                 return false;
             }
 
-            var name = element.Value.Trim();
             if (Regex.IsMatch(name, @"(UnitTests|IntegrationTests)$", RegexOptions.IgnoreCase) && !data.IsAnyUnitTest)
             {
                 textWriter.WriteLine($"Assembly named {name} is not marked as a unit test");