Add failing test

Youssef1313 · Mar 6, 2022 · eef482e · eef482e
1 parent b30ecba
commit eef482e
Showing 1 changed file with 29 additions and 3 deletions.
diff --git a/src/Compilers/CSharp/Test/Syntax/IncrementalParsing/IncrementalParsingTests.cs b/src/Compilers/CSharp/Test/Syntax/IncrementalParsing/IncrementalParsingTests.cs
@@ -28,13 +28,19 @@ private SyntaxTree Parse(string text, params string[] defines)
             return SyntaxFactory.ParseSyntaxTree(itext, options);
         }
 
-        private SyntaxTree Parse6(string text)
+        private SyntaxTree Parse(string text, LanguageVersion languageVersion)
         {
-            var options = new CSharpParseOptions(languageVersion: LanguageVersion.CSharp6);
+            var options = new CSharpParseOptions(languageVersion: languageVersion);
             var itext = SourceText.From(text);
             return SyntaxFactory.ParseSyntaxTree(itext, options);
         }
 
+        private SyntaxTree Parse6(string text)
+            => Parse(text, LanguageVersion.CSharp6);
+
+        private SyntaxTree ParsePreview(string text)
+            => Parse(text, LanguageVersion.Preview);
+
         [Fact]
         public void TestChangeClassNameWithNonMatchingMethod()
         {
@@ -51,6 +57,27 @@ public void TestChangeClassNameWithNonMatchingMethod()
                             SyntaxKind.IdentifierToken);
         }
 
+        [Fact]
+        public void Test()
+        {
+            var text = @"#nullable enable
+
+public class C {
+    public void M(string? x  !!) { // no error.
+    }
+}";
+            var oldTree = this.ParsePreview(text);
+            var newTree = oldTree.WithReplaceFirst("?", "");
+            Assert.Equal(0, oldTree.GetCompilationUnitRoot().Errors().Length);
+
+            // following assert fails.
+            // newTree has "error CS1003: Syntax error, ',' expected"
+            Assert.Equal(0, newTree.GetCompilationUnitRoot().Errors().Length);
+
+            var diffs = SyntaxDifferences.GetRebuiltNodes(oldTree, newTree);
+            TestDiffsInOrder(diffs);
+        }
+
         [Fact]
         public void TestChangeClassNameToNotMatchConstructor()
         {
@@ -432,7 +459,6 @@ public void TestStatementToGlobalStatementChange()
                             SyntaxKind.IdentifierName,
                             SyntaxKind.SemicolonToken);
         }
-
         #region "Regression"
 
 #if false