Single-line comment tokenization accuracy improved.

Author: RyanLamansky

SqlServerSimulator.Tests/SimpleCommandTests.cs

@@ -27,83 +27,45 @@ public void CommandNotInitialized()
     [TestMethod]
     public void EmptyCommand()
     {
-        using var connection = new Simulation().CreateDbConnection();
-        connection.Open();
-
-        using var command = connection.CreateCommand("");
-
-        var x = Throws<InvalidOperationException>(command.ExecuteReader);
+        var x = Throws<InvalidOperationException>(new Simulation().CreateCommand("").ExecuteReader);
         AreEqual("ExecuteReader: CommandText property has not been initialized", x.Message);
     }
 
     [TestMethod]
     public void SpaceCommand()
     {
-        using var connection = new Simulation().CreateDbConnection();
-        connection.Open();
-
-        using var command = connection.CreateCommand(" ");
-        using var reader = command.ExecuteReader();
-
-        IsFalse(reader.Read());
+        IsFalse(new Simulation().ExecuteReader(" ").Read());
     }
 
     [TestMethod]
     public void IncompleteSingleLineCommentCommand()
     {
-        using var connection = new Simulation().CreateDbConnection();
-        connection.Open();
-
-        using var command = connection.CreateCommand("-");
-        _ = Throws<DbException>(command.ExecuteReader);
-    }
-
-    [TestMethod]
-    public void SingleLineEmptyCommentCommand()
-    {
-        using var connection = new Simulation().CreateDbConnection();
-        connection.Open();
-
-        using var command = connection.CreateCommand("--");
-        using var reader = command.ExecuteReader();
-
-        IsFalse(reader.Read());
+        _ = Throws<DbException>(() => new Simulation().ExecuteReader("-"));
     }
 
     [TestMethod]
-    public void SingleLineCommentCommand()
+    [DataRow("--")]
+    [DataRow("--Test")]
+    [DataRow("--Test \n")]
+    [DataRow("--Test \r")]
+    [DataRow("--Test \r\n")]
+    [DataRow("--Test\n")]
+    [DataRow("--Test\r")]
+    [DataRow("--Test\r\n")]
+    public void LineComment(string comment)
     {
-        using var connection = new Simulation().CreateDbConnection();
-        connection.Open();
-
-        using var command = connection.CreateCommand("-- Test");
-        using var reader = command.ExecuteReader();
-
-        IsFalse(reader.Read());
-    }
-
-    [TestMethod]
-    public void SingleLineCommentWithNewlineCommand()
-    {
-        using var connection = new Simulation().CreateDbConnection();
-        connection.Open();
-
-        using var command = connection.CreateCommand("-- Test\n");
-        using var reader = command.ExecuteReader();
-
-        IsFalse(reader.Read());
-    }
-
-    [TestMethod]
-    public void SingleLineCommentWithCarriageReturnCommand()
-    {
-        using var connection = new Simulation().CreateDbConnection();
-        connection.Open();
-
-        using var command = connection.CreateCommand("-- Test\r");
-        using var reader = command.ExecuteReader();
-
-        IsFalse(reader.Read());
+        IsNull(new Simulation().ExecuteScalar($"{comment}"));
+        AreEqual(1, new Simulation().ExecuteScalar<int>($"select 1 {comment}"));
+        AreEqual(2, new Simulation().ExecuteScalar<int>($"select 2{comment}"));
+        AreEqual(3, new Simulation().ExecuteScalar<int>($"select 3\n{comment}"));
+        AreEqual(4, new Simulation().ExecuteScalar<int>($"select 4 \n{comment}"));
+        AreEqual(5, new Simulation().ExecuteScalar<int>($"select 5\r{comment}"));
+        AreEqual(6, new Simulation().ExecuteScalar<int>($"select 6 \r{comment}"));
+        AreEqual(7, new Simulation().ExecuteScalar<int>($"select 7\r\n{comment}"));
+        AreEqual(8, new Simulation().ExecuteScalar<int>($"select 8 \r\n{comment}"));
+        AreEqual(9, new Simulation().ExecuteScalar<int>($"{comment}\nselect 9"));
+        AreEqual(10, new Simulation().ExecuteScalar<int>($"{comment}\rselect 10"));
+        AreEqual(11, new Simulation().ExecuteScalar<int>($"{comment}\r\nselect 11"));
     }
 
     [TestMethod]

SqlServerSimulator/Parser/Token.cs

@@ -14,7 +14,10 @@ abstract class Token
 
     private protected Token(string command, int index, int length)
     {
+        System.Diagnostics.Debug.Assert(index >= 0);
+        System.Diagnostics.Debug.Assert(length > 0);
         System.Diagnostics.Debug.Assert(index + length <= command.Length);
+
         this.command = command;
         this.index = index;
         this.length = length;

SqlServerSimulator/Parser/Tokens/Comment.cs

@@ -4,13 +4,16 @@ sealed class Comment : Token
 {
     private Comment(string command, int index, int length) : base(command, index, length)
     {
+        System.Diagnostics.Debug.Assert(length >= 2);
+        System.Diagnostics.Debug.Assert(command[index] is '/' or '-' && command[index + 1] is '*' or '-');
+        System.Diagnostics.Debug.Assert(command[index] is not '/' || length >= 4);
     }
 
     /// <summary>
     /// Parses a single-line comment (`-- ...`) where the initial `--` has already been consumed.
     /// </summary>
-    /// <param name="start">The position of the opening `/`.</param>
-    /// <param name="index">Initially after the opening `*`, updated to just after the closing `/`.</param>
+    /// <param name="start">The position of the `--`.</param>
+    /// <param name="index">Initially after the opening `--`, updated to just after the end of the line.</param>
     /// <param name="command">The raw command to parse.</param>
     /// <returns>A <see cref="Comment"/>.</returns>
     public static Comment ParseSingleLine(int start, ref int index, string command)
@@ -21,11 +24,13 @@ public static Comment ParseSingleLine(int start, ref int index, string command)
             {
                 case '\r':
                 case '\n':
-                    return new Comment(command, start, --index);
+                    return new Comment(command, start, index-- - start);
             }
         }
 
-        return new Comment(command, start, --index);
+        index--;
+
+        return new Comment(command, start, 2);
     }
 
     /// <summary>