[wasm][debugger] Fix expression evaluation when it is a reference (#41135)

* [wasm][debugger] Fix expression evaluation when it is a reference

.. preceded by spaces. Eg: `"  foo.dateTime", or `"  foo.count"`

* Explanation of the fix:

- these particular expressions end up in the code path where we get a
SimpleMemberAccessExpression, and only one member access (like `a.b.c`)
was found.

- that code path had
    `return memberAccessValues[0]?["value"]?.Value<JObject>();`

  - which is incorrect, and we need to return `memberAccessValues[0]`,
  which is the value itself.

Author: radical

src/mono/wasm/debugger/BrowserDebugProxy/EvaluateExpression.cs

@@ -213,6 +213,7 @@ private static async Task<IList<JObject>> ResolveIdentifiers(IEnumerable<Identif
 
         internal static async Task<JObject> CompileAndRunTheExpression(string expression, MemberReferenceResolver resolver, CancellationToken token)
         {
+            expression = expression.Trim();
             SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(@"
                 using System;
                 public class CompileAndRunTheExpression
@@ -245,10 +246,10 @@ public static object Evaluate()
 
             var memberAccessValues = await ResolveMemberAccessExpressions(findVarNMethodCall.memberAccesses, resolver, token);
 
-            // this.dateTime
+            // eg. "this.dateTime", "  dateTime.TimeOfDay"
             if (expressionTree.Kind() == SyntaxKind.SimpleMemberAccessExpression && findVarNMethodCall.memberAccesses.Count == 1)
             {
-                return memberAccessValues[0]?["value"]?.Value<JObject>();
+                return memberAccessValues[0];
             }
 
             var identifierValues = await ResolveIdentifiers(findVarNMethodCall.identifiers, resolver, token);

src/mono/wasm/debugger/BrowserDebugProxy/MonoProxy.cs

@@ -700,7 +700,7 @@ async Task<bool> OnEvaluateOnCallFrame(MessageId msg_id, int scope_id, string ex
                 }
                 else
                 {
-                    SendResponse(msg_id, Result.Err($"Unable to evaluate {expression}"), token);
+                    SendResponse(msg_id, Result.Err($"Unable to evaluate '{expression}'"), token);
                 }
             }
             catch (ReturnAsErrorException ree)

src/mono/wasm/debugger/DebuggerTestSuite/EvaluateOnCallFrameTests.cs

@@ -49,22 +49,26 @@ public async Task EvaluateTypeInstanceMembers(string prefix, int bias, string ty
                var dateTime = new DateTime(2010, 9, 8, 7, 6, 5 + bias);
                var DTProp = dateTime.AddMinutes(10);
 
-               await EvaluateOnCallFrameAndCheck(id,
-                   (prefix + "a", TNumber(4)),
-
-                   // fields
-                   (prefix + "dateTime.TimeOfDay", TValueType("System.TimeSpan", dateTime.TimeOfDay.ToString())),
-                   (prefix + "dateTime", TDateTime(dateTime)),
-                   (prefix + "dateTime.TimeOfDay.Minutes", TNumber(dateTime.TimeOfDay.Minutes)),
-
-                   // properties
-                   (prefix + "DTProp.TimeOfDay.Minutes", TNumber(DTProp.TimeOfDay.Minutes)),
-                   (prefix + "DTProp", TDateTime(DTProp)),
-                   (prefix + "DTProp.TimeOfDay", TValueType("System.TimeSpan", DTProp.TimeOfDay.ToString())),
-
-                   (prefix + "IntProp", TNumber(9)),
-                   (prefix + "NullIfAIsNotZero", TObject("DebuggerTests.EvaluateTestsClassWithProperties", is_null: true))
-               );
+                foreach (var pad in new[] { String.Empty, "  " })
+                {
+                    var padded_prefix = pad + prefix;
+                    await EvaluateOnCallFrameAndCheck(id,
+                        ($"{padded_prefix}a", TNumber(4)),
+
+                        // fields
+                        ($"{padded_prefix}dateTime.TimeOfDay", TValueType("System.TimeSpan", dateTime.TimeOfDay.ToString())),
+                        ($"{padded_prefix}dateTime", TDateTime(dateTime)),
+                        ($"{padded_prefix}dateTime.TimeOfDay.Minutes", TNumber(dateTime.TimeOfDay.Minutes)),
+
+                        // properties
+                        ($"{padded_prefix}DTProp.TimeOfDay.Minutes", TNumber(DTProp.TimeOfDay.Minutes)),
+                        ($"{padded_prefix}DTProp", TDateTime(DTProp)),
+                        ($"{padded_prefix}DTProp.TimeOfDay", TValueType("System.TimeSpan", DTProp.TimeOfDay.ToString())),
+
+                        ($"{padded_prefix}IntProp", TNumber(9)),
+                        ($"{padded_prefix}NullIfAIsNotZero", TObject("DebuggerTests.EvaluateTestsClassWithProperties", is_null: true))
+                    );
+                }
            });
 
         [Theory]
@@ -104,12 +108,15 @@ public async Task EvaluateMethodLocals(string type, string method, string bp_fun
                var dt = new DateTime(2025, 3, 5, 7, 9, 11);
                await EvaluateOnCallFrameAndCheck(id,
                    ("d", TNumber(401)),
+                   (" d", TNumber(401)),
                    ("e", TNumber(402)),
                    ("f", TNumber(403)),
 
                    // property on a local
                    ("local_dt", TDateTime(dt)),
-                   ("local_dt.Date", TDateTime(dt.Date)));
+                   ("  local_dt", TDateTime(dt)),
+                   ("local_dt.Date", TDateTime(dt.Date)),
+                   ("  local_dt.Date", TDateTime(dt.Date)));
            });
 
         [Fact]
@@ -212,8 +219,10 @@ await EvaluateOnCallFrameAndCheck(id,
                    // "((dt))", TObject("foo")); //FIXME:
 
                    ("this", TObject("DebuggerTests.EvaluateTestsClass.TestEvaluate")),
+                   ("  this", TObject("DebuggerTests.EvaluateTestsClass.TestEvaluate")),
 
                    ("5", TNumber(5)),
+                   ("  5", TNumber(5)),
                    ("d + e", TNumber(203)),
                    ("e + 10", TNumber(112)),