Merged PR 2331: fix custom logging when using the TestingEngine

Fix logging when using TestEngine directory so the logger provided to the test engine contains the actual test output.

Related work items: #4066

Source/Core/IO/Logging/InMemoryLogger.cs

@@ -26,6 +26,11 @@ namespace Microsoft.Coyote.IO
         /// </summary>
         private readonly object Lock;
 
+        /// <summary>
+        /// Optional logger provided by the user to delegate logging to.
+        /// </summary>
+        internal TextWriter UserLogger { get; set; }
+
         /// <summary>
         /// When overridden in a derived class, returns the character encoding in which the
         /// output is written.
@@ -52,6 +57,10 @@ namespace Microsoft.Coyote.IO
                 lock (this.Lock)
                 {
                     this.Builder.Append(value);
+                    if (this.UserLogger != null)
+                    {
+                        this.UserLogger.WriteLine(value);
+                    }
                 }
             }
             catch (ObjectDisposedException)
@@ -70,6 +79,10 @@ namespace Microsoft.Coyote.IO
                 lock (this.Lock)
                 {
                     this.Builder.Append(value);
+                    if (this.UserLogger != null)
+                    {
+                        this.UserLogger.WriteLine(value);
+                    }
                 }
             }
             catch (ObjectDisposedException)
@@ -89,6 +102,10 @@ namespace Microsoft.Coyote.IO
                 lock (this.Lock)
                 {
                     this.Builder.AppendLine(value);
+                    if (this.UserLogger != null)
+                    {
+                        this.UserLogger.WriteLine(value);
+                    }
                 }
             }
             catch (ObjectDisposedException)

Source/Test/SystematicTesting/TestingEngine.cs

@@ -76,6 +76,11 @@ namespace Microsoft.Coyote.SystematicTesting
         /// </remarks>
         private TextWriter Logger;
 
+        /// <summary>
+        /// The default logger that is used during testing.
+        /// </summary>
+        private readonly TextWriter DefaultLogger;
+
         /// <summary>
         /// The profiler.
         /// </summary>
@@ -204,7 +209,8 @@ namespace Microsoft.Coyote.SystematicTesting
             this.Configuration = configuration;
             this.TestMethodInfo = testMethodInfo;
 
-            this.Logger = new ConsoleLogger();
+            this.DefaultLogger = new ConsoleLogger();
+            this.Logger = this.DefaultLogger;
             this.ErrorReporter = new ErrorReporter(configuration, this.Logger);
             this.Profiler = new Profiler();
 
@@ -488,12 +494,21 @@ namespace Microsoft.Coyote.SystematicTesting
                 if (!this.Configuration.IsVerbose)
                 {
                     runtimeLogger = new InMemoryLogger();
+                    if (this.Logger != this.DefaultLogger)
+                    {
+                        runtimeLogger.UserLogger = this.Logger;
+                    }
+
                     runtime.SetLogger(runtimeLogger);
 
                     var writer = TextWriter.Null;
                     Console.SetOut(writer);
                     Console.SetError(writer);
                 }
+                else if (this.Logger != this.DefaultLogger)
+                {
+                    runtime.SetLogger(this.Logger);
+                }
 
                 this.InitializeCustomLogging(runtime);
 
@@ -949,9 +964,15 @@ namespace Microsoft.Coyote.SystematicTesting
         /// <summary>
         /// Installs the specified <see cref="TextWriter"/>.
         /// </summary>
-        public void SetLogger(TextWriter logger)
+        /// <param name="logger">The logger to install.</param>
+        /// <returns>The previously installed logger.</returns>
+        public TextWriter SetLogger(TextWriter logger)
         {
-            this.Logger.Dispose();
+            TextWriter oldLoger = null;
+            if (this.Logger != this.DefaultLogger)
+            {
+                oldLoger = this.Logger;
+            }
 
             if (logger is null)
             {
@@ -963,6 +984,7 @@ namespace Microsoft.Coyote.SystematicTesting
             }
 
             this.ErrorReporter.Logger = logger;
+            return oldLoger;
         }
     }
 }

Tests/SystematicTesting.Tests/Tasks/Logging/CustomTaskRuntimeLogTests.cs

@@ -0,0 +1,53 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.IO;
+using System.Text.RegularExpressions;
+using Microsoft.Coyote.Runtime;
+using Microsoft.Coyote.Tests.Common;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace Microsoft.Coyote.SystematicTesting.Tests.Tasks
+{
+    public class CustomTaskRuntimeLogTests : BaseTest
+    {
+        public CustomTaskRuntimeLogTests(ITestOutputHelper output)
+            : base(output)
+        {
+        }
+
+        public override bool SystematicTest => true;
+
+        [Fact(Timeout = 5000)]
+        public void TestCustomLogger()
+        {
+            StringWriter log = new StringWriter();
+
+            var config = Configuration.Create().WithVerbosityEnabled().WithTestingIterations(3);
+            TestingEngine engine = TestingEngine.Create(config, (ICoyoteRuntime runtime) =>
+            {
+                runtime.Logger.WriteLine("Hi mom!");
+            });
+
+            engine.SetLogger(log);
+            engine.Run();
+
+            var result = log.ToString();
+            result = RemoveNonDeterministicValuesFromReport(result);
+            var expected = RemoveNonDeterministicValuesFromReport(@"... Task 0 is using 'random' strategy (seed:4005173804).
+..... Iteration #1
+<TestLog> Running test.
+Hi mom!
+..... Iteration #2
+<TestLog> Running test.
+Hi mom!
+..... Iteration #3
+<TestLog> Running test.
+Hi mom!
+");
+
+            Assert.Equal(expected, result);
+        }
+    }
+}

docs/_learn/ref/Microsoft.Coyote.SystematicTesting/TestingEngine/SetLogger.md

@@ -9,9 +9,17 @@ permalink: /learn/ref/Microsoft.Coyote.SystematicTesting/TestingEngine/SetLogger
 Installs the specified TextWriter.
 
 ```csharp
-public void SetLogger(TextWriter logger)
+public TextWriter SetLogger(TextWriter logger)
 ```
 
+| parameter | description |
+| --- | --- |
+| logger | The logger to install. |
+
+## Return Value
+
+The previously installed logger.
+
 ## See Also
 
 * class [TestingEngine](../TestingEngineType)