More test fixups

src/EditorFeatures/CSharpTest/CodeActions/LambdaSimplifier/LambdaSimplifierTests.cs

@@ -397,7 +397,7 @@ static void Main()
     }
 }";
 
-            await TestInRegularAndScriptAsync(code, expected);
+            await TestInRegularAndScriptAsync(code, expected, parseOptions: TestOptions.Regular7_3);
         }
 
         [WorkItem(627092, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/627092")]

src/EditorFeatures/CSharpTest/UseNamedArguments/UseNamedArgumentsTests.cs

@@ -336,9 +336,9 @@ void M(int arg1, int arg2)
 }",
 @"class C
 {
-    void M(int arg1, int arg2) 
+    void M(int arg1, int arg2)
         => M(arg1: 1 + 2, 2);
-}");
+}", parameters: new TestParameters(parseOptions: TestOptions.Regular7_3));
         }
 
         [WorkItem(18848, "https://github.com/dotnet/roslyn/issues/18848")]

src/VisualStudio/Core/Test/CodeModel/CSharp/CodeClassTests.vb

@@ -2160,7 +2160,7 @@ class C
 {
     string Name
     {
-        get => default;
+        get => default(string);
         set
         {
         }
@@ -2188,7 +2188,7 @@ class C
     {
         get
         {
-            return default;
+            return default(string);
         }
 
         set
@@ -2220,7 +2220,7 @@ class C$$
 <Code>
 class C
 {
-    string Name => default;
+    string Name => default(string);
 }
 </Code>
 
@@ -2244,7 +2244,7 @@ class C
     {
         get
         {
-            return default;
+            return default(string);
         }
     }
 }