From 1ac8ff104e0153abdc5c74e6f6645bf5af3c1960 Mon Sep 17 00:00:00 2001
From: Steve Sanderson <SteveSandersonMS@users.noreply.github.com>
Date: Sun, 29 Sep 2019 22:06:09 +0100
Subject: [PATCH] Add specific unit test in ParameterViewTest

---
 .../Components/test/ParameterViewTest.cs      | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/src/Components/Components/test/ParameterViewTest.cs b/src/Components/Components/test/ParameterViewTest.cs
index 8aad6c9140..5193e8fe29 100644
--- a/src/Components/Components/test/ParameterViewTest.cs
+++ b/src/Components/Components/test/ParameterViewTest.cs
@@ -322,6 +322,32 @@ namespace Microsoft.AspNetCore.Components
             Assert.Same(myEntryValue, result);
         }
 
+        [Fact]
+        public void CannotReadAfterLifetimeExpiry()
+        {
+            // Arrange
+            var builder = new RenderBatchBuilder();
+            var lifetime = new ParameterViewLifetime(builder);
+            var frames = new[]
+            {
+                RenderTreeFrame.ChildComponent(0, typeof(FakeComponent)).WithComponentSubtreeLength(1)
+            };
+            var parameterView = new ParameterView(lifetime, frames, 0);
+
+            // Act
+            builder.InvalidateParameterViews();
+
+            // Assert
+            Assert.Throws<InvalidOperationException>(() => parameterView.GetEnumerator());
+            Assert.Throws<InvalidOperationException>(() => parameterView.GetValueOrDefault<object>("anything"));
+            Assert.Throws<InvalidOperationException>(() => parameterView.SetParameterProperties(new object()));
+            Assert.Throws<InvalidOperationException>(() => parameterView.ToDictionary());
+            var ex = Assert.Throws<InvalidOperationException>(() => parameterView.TryGetValue<object>("anything", out _));
+
+            // It's enough to assert about one of the messages
+            Assert.Equal($"The {nameof(ParameterView)} instance can no longer be read because it has expired. {nameof(ParameterView)} can only be read synchronously and must not be stored for later use.", ex.Message);
+        }
+
         private Action<ParameterValue> AssertParameter(string expectedName, object expectedValue, bool expectedIsCascading)
         {
             return parameter =>