Fix LazyTests.Ctor_ExceptionRecovery test

On AoT, XUnit itself was invoking the Lazy object's
Value property behind our backs. This particular
test is sensitive to that.

(The reason why this was happening on AoT
and not CoreClr was because CoreClr finds
Lazy's ToString() override and invokes that.
We could make the same happen pm AoT with an rd.xml
but it's simply more reliable not to
give XUnit a chance to meddle in the first
place.)

Author: Atsushi Kanamori

src/System.Runtime/tests/System/LazyTests.cs

@@ -150,27 +150,35 @@ public InitiallyExceptionThrowingCtor()
             }
         }
 
-        public static IEnumerable<object[]> Ctor_ExceptionRecovery_MemberData()
+        private static IEnumerable<Lazy<InitiallyExceptionThrowingCtor>> Ctor_ExceptionRecovery_MemberData()
         {
-            yield return new object[] { new Lazy<InitiallyExceptionThrowingCtor>(), 5 };
-            yield return new object[] { new Lazy<InitiallyExceptionThrowingCtor>(true), 5 };
-            yield return new object[] { new Lazy<InitiallyExceptionThrowingCtor>(false), 5 };
-            yield return new object[] { new Lazy<InitiallyExceptionThrowingCtor>(LazyThreadSafetyMode.ExecutionAndPublication), 5 };
-            yield return new object[] { new Lazy<InitiallyExceptionThrowingCtor>(LazyThreadSafetyMode.None), 5 };
-            yield return new object[] { new Lazy<InitiallyExceptionThrowingCtor>(LazyThreadSafetyMode.PublicationOnly), 5 };
+            yield return new Lazy<InitiallyExceptionThrowingCtor>();
+            yield return new Lazy<InitiallyExceptionThrowingCtor>(true);
+            yield return new Lazy<InitiallyExceptionThrowingCtor>(false);
+            yield return new Lazy<InitiallyExceptionThrowingCtor>(LazyThreadSafetyMode.ExecutionAndPublication);
+            yield return new Lazy<InitiallyExceptionThrowingCtor>(LazyThreadSafetyMode.None);
+            yield return new Lazy<InitiallyExceptionThrowingCtor>(LazyThreadSafetyMode.PublicationOnly);
         }
 
-        [Theory]
-        [MemberData(nameof(Ctor_ExceptionRecovery_MemberData))]
-        public static void Ctor_ExceptionRecovery(Lazy<InitiallyExceptionThrowingCtor> lazy, int expected)
+        //
+        // Do not use [Theory]. XUnit argument formatter can invoke the lazy.Value property underneath you and ruin the assumptions
+        // made by the test.
+        //
+        [Fact]
+        public static void Ctor_ExceptionRecovery()
         {
-            InitiallyExceptionThrowingCtor.counter = 0;
-            InitiallyExceptionThrowingCtor result = null;
-            for (var i = 0; i < 10; ++i)
+            foreach (Lazy<InitiallyExceptionThrowingCtor> lazy in Ctor_ExceptionRecovery_MemberData())
             {
-                try { result = lazy.Value; } catch (Exception) { }
+                InitiallyExceptionThrowingCtor.counter = 0;
+                InitiallyExceptionThrowingCtor result = null;
+                for (int i = 0; i < 10; ++i)
+                {
+                    try
+                    { result = lazy.Value; }
+                    catch (Exception) { }
+                }
+                Assert.Equal(5, result.Value);
             }
-            Assert.Equal(result.Value, expected);
         }
 
         private static void Value_ExceptionRecovery_IntImpl(Lazy<int> lazy, ref int counter, int expected)