Fix: creating a locator should not affect static state

src/lib-csharp/Locators/IVelopackLocator.cs

@@ -57,6 +57,12 @@ namespace Velopack.Locators
         /// </summary>
         IProcessImpl Process { get; }
         
+        /// <summary>
+        /// Add a logger to the list of loggers. This will be used to log messages from Velopack.
+        /// </summary>
+        /// <param name="logger"></param>
+        void AddLogger(IVelopackLogger logger);
+        
         /// <summary>
         /// Finds .nupkg files in the PackagesDir and returns a list of ReleaseEntryName objects.
         /// </summary>

src/lib-csharp/Locators/LinuxVelopackLocator.cs

@@ -36,9 +36,6 @@ namespace Velopack.Locators
         /// <inheritdoc />
         public override string? Channel { get; }
 
-        /// <inheritdoc />
-        public override IVelopackLogger Log { get; }
-
         /// <inheritdoc />
         public override string? AppTempDir => CreateSubDirIfDoesNotExist(TempUtil.GetDefaultTempBaseDirectory(), AppId);
 
@@ -63,15 +60,13 @@ namespace Velopack.Locators
             if (!VelopackRuntimeInfo.IsLinux)
                 throw new NotSupportedException($"Cannot instantiate {nameof(LinuxVelopackLocator)} on a non-linux system.");
 
-            var combinedLog = new CombinedVelopackLogger();
+            CombinedLogger = new CombinedVelopackLogger(customLog);
-            combinedLog.Add(customLog);
-            Log = combinedLog;
 
-            Process = processImpl ??= new DefaultProcessImpl(combinedLog);
+            Process = processImpl ??= new DefaultProcessImpl(CombinedLogger);
             var ourPath = processImpl.GetCurrentProcessPath();
             var currentProcessId = processImpl.GetCurrentProcessId();
 
-            using var initLog = new CachedVelopackLogger(combinedLog);
+            using var initLog = new CachedVelopackLogger(CombinedLogger);
             initLog.Info($"Initializing {nameof(LinuxVelopackLocator)}");
             var logFilePath = Path.Combine(Path.GetTempPath(), DefaultLoggingFileName);
 
@@ -107,7 +102,7 @@ namespace Velopack.Locators
 
             try {
                 var fileLog = new FileVelopackLogger(logFilePath, currentProcessId);
-                combinedLog.Add(fileLog);
+                CombinedLogger.Add(fileLog);
             } catch (Exception ex) {
                 initLog.Error("Unable to create file logger: " + ex);
             }

src/lib-csharp/Locators/OsxVelopackLocator.cs

@@ -39,9 +39,6 @@ namespace Velopack.Locators
         /// <inheritdoc />
         public override string? PackagesDir => CreateSubDirIfDoesNotExist(CachesAppDir, "packages");
 
-        /// <inheritdoc />
-        public override IVelopackLogger Log { get; }
-
         private string? CachesAppDir => CreateSubDirIfDoesNotExist(CachesVelopackDir, AppId);
         private string? CachesVelopackDir => CreateSubDirIfDoesNotExist(CachesDir, "velopack");
         private string? CachesDir => CreateSubDirIfDoesNotExist(LibraryDir, "Caches");
@@ -60,15 +57,13 @@ namespace Velopack.Locators
             if (!VelopackRuntimeInfo.IsOSX)
                 throw new NotSupportedException($"Cannot instantiate {nameof(OsxVelopackLocator)} on a non-osx system.");
 
-            var combinedLog = new CombinedVelopackLogger();
+            CombinedLogger = new CombinedVelopackLogger(customLog);
-            combinedLog.Add(customLog);
-            Log = combinedLog;
             
-            Process = processImpl ??= new DefaultProcessImpl(combinedLog);
+            Process = processImpl ??= new DefaultProcessImpl(CombinedLogger);
             var ourPath = processImpl.GetCurrentProcessPath();
             var currentProcessId = processImpl.GetCurrentProcessId();
 
-            using var initLog = new CachedVelopackLogger(combinedLog);
+            using var initLog = new CachedVelopackLogger(CombinedLogger);
             initLog.Info($"Initializing {nameof(OsxVelopackLocator)}");
 
             string logFolder = Path.GetTempPath();
@@ -107,7 +102,7 @@ namespace Velopack.Locators
             try {
                 var logFilePath = Path.Combine(logFolder, logFileName);
                 var fileLog = new FileVelopackLogger(logFilePath, currentProcessId);
-                combinedLog.Add(fileLog);
+                CombinedLogger.Add(fileLog);
             } catch (Exception ex) {
                 initLog.Error("Unable to create file logger: " + ex);
             }

src/lib-csharp/Locators/VelopackLocator.cs

@@ -15,7 +15,7 @@ namespace Velopack.Locators
     public abstract class VelopackLocator : IVelopackLocator
     {
         private static IVelopackLocator? _current;
-        
+
         /// <summary>
         /// The default log file name for Velopack.
         /// </summary>
@@ -34,7 +34,8 @@ namespace Velopack.Locators
             get {
                 if (_current == null)
                     throw new InvalidOperationException(
-                        $"No VelopackLocator has been set. Either call {nameof(VelopackApp)}.{nameof(VelopackApp.Build)}() or provide {nameof(IVelopackLocator)} as a method parameter.");
+                        $"No VelopackLocator has been set. Either call {nameof(VelopackApp)}.{nameof(VelopackApp.Build)}().Run() " +
+                        $"or provide {nameof(IVelopackLocator)} as a method parameter.");
                 return _current;
             }
         }
@@ -43,13 +44,13 @@ namespace Velopack.Locators
         public static IVelopackLocator CreateDefaultForPlatform(IProcessImpl? processImpl = null, IVelopackLogger? logger = null)
         {
             if (VelopackRuntimeInfo.IsWindows)
-                return _current = new WindowsVelopackLocator(processImpl, logger);
+                return new WindowsVelopackLocator(processImpl, logger);
 
             if (VelopackRuntimeInfo.IsOSX)
-                return _current = new OsxVelopackLocator(processImpl, logger);
+                return new OsxVelopackLocator(processImpl, logger);
 
             if (VelopackRuntimeInfo.IsLinux)
-                return _current = new LinuxVelopackLocator(processImpl, logger);
+                return new LinuxVelopackLocator(processImpl, logger);
 
             throw new PlatformNotSupportedException($"OS platform '{VelopackRuntimeInfo.SystemOs.GetOsLongName()}' is not supported.");
         }
@@ -87,7 +88,7 @@ namespace Velopack.Locators
         public abstract string? Channel { get; }
 
         /// <inheritdoc/>
-        public abstract IVelopackLogger Log { get; }
+        public virtual IVelopackLogger Log => ((IVelopackLogger?) CombinedLogger) ?? new NullVelopackLogger();
 
         /// <inheritdoc/>
         public virtual bool IsPortable => false;
@@ -111,6 +112,14 @@ namespace Velopack.Locators
         /// <inheritdoc/>
         public abstract SemanticVersion? CurrentlyInstalledVersion { get; }
 
+        internal CombinedVelopackLogger? CombinedLogger { get; set; }
+
+        /// <inheritdoc/>
+        public void AddLogger(IVelopackLogger logger)
+        {
+            CombinedLogger?.Add(logger);
+        }
+
         /// <inheritdoc/>
         public virtual List<VelopackAsset> GetLocalPackages()
         {

src/lib-csharp/Locators/WindowsVelopackLocator.cs

@@ -37,9 +37,6 @@ namespace Velopack.Locators
         /// <inheritdoc />
         public override string? PackagesDir => _packagesDir.Value;
 
-        /// <inheritdoc />
-        public override IVelopackLogger Log { get; }
-
         /// <inheritdoc />
         public override bool IsPortable => RootAppDir != null && File.Exists(Path.Combine(RootAppDir, ".portable"));
 
@@ -56,16 +53,13 @@ namespace Velopack.Locators
                 throw new NotSupportedException($"Cannot instantiate {nameof(WindowsVelopackLocator)} on a non-Windows system.");
 
             _packagesDir = new(GetPackagesDir);
+            CombinedLogger = new CombinedVelopackLogger(customLog);
 
-            var combinedLog = new CombinedVelopackLogger();
+            Process = processImpl ??= new DefaultProcessImpl(CombinedLogger);
-            combinedLog.Add(customLog);
-            Log = combinedLog;
-
-            Process = processImpl ??= new DefaultProcessImpl(combinedLog);
             var ourPath = processImpl.GetCurrentProcessPath();
             var currentProcessId = processImpl.GetCurrentProcessId();
 
-            using var initLog = new CachedVelopackLogger(combinedLog);
+            using var initLog = new CachedVelopackLogger(CombinedLogger);
             initLog.Info($"Initializing {nameof(WindowsVelopackLocator)}");
 
             // We try various approaches here. Firstly, if Update.exe is in the parent directory,
@@ -133,6 +127,7 @@ namespace Velopack.Locators
                     Directory.CreateDirectory(TempAppRootDirectory);
                     File.Copy(UpdateExePath, tempTargetUpdateExe);
                 }
+
                 UpdateExePath = tempTargetUpdateExe;
             }
 
@@ -142,7 +137,7 @@ namespace Velopack.Locators
                 try {
                     var logFilePath = Path.Combine(RootAppDir, DefaultLoggingFileName);
                     var fileLog = new FileVelopackLogger(logFilePath, currentProcessId);
-                    combinedLog.Add(fileLog);
+                    CombinedLogger.Add(fileLog);
                     //fileLogCreated = true;
                 } catch (Exception ex) {
                     fileLogException = ex;
@@ -156,7 +151,7 @@ namespace Velopack.Locators
                     var logFileName = String.IsNullOrEmpty(AppId) ? DefaultLoggingFileName : $"velopack_{AppId}.log";
                     var logFilePath = Path.Combine(Path.GetTempPath(), logFileName);
                     var fileLog = new FileVelopackLogger(logFilePath, currentProcessId);
-                    combinedLog.Add(fileLog);
+                    CombinedLogger.Add(fileLog);
                 } catch (Exception ex) {
                     tempFileLogException = ex;
                 }

src/lib-csharp/Logging/CombinedVelopackLogger.cs

@@ -8,6 +8,15 @@ namespace Velopack.Logging
     {
         private readonly List<IVelopackLogger> _loggers = new();
 
+        public CombinedVelopackLogger(params IVelopackLogger?[] loggers)
+        {
+            foreach (var logger in loggers) {
+                if (logger != null) {
+                    _loggers.Add(logger);
+                }
+            }
+        }
+
         public void Log(VelopackLogLevel logLevel, string? message, Exception? exception)
         {
             foreach (var logger in _loggers) {

test/TestApp/Program.cs

@@ -4,7 +4,7 @@ using Velopack;
 using Velopack.Locators;
 using Velopack.Logging;
 
-var locator = VelopackLocator.CreateDefaultForPlatform(new ConsoleVelopackLogger());
+var locator = VelopackLocator.CreateDefaultForPlatform(logger: new ConsoleVelopackLogger());
 
 try {
     bool shouldExit = false;