Streamlines error message prefixes (#218)

src/BuildScriptGeneratorCli/BuildScriptGenerator.cs

@@ -76,7 +76,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
             catch (InvalidUsageException ex)
             {
                 _logger.LogError(ex, "Invalid usage");
-                _console.Error.WriteLine(ex.Message);
+                _console.WriteErrorLine(ex.Message);
                 return false;
             }
         }

src/BuildScriptGeneratorCli/Commands/BuildCommand.cs

@@ -209,6 +209,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
                     return;
                 }
 
+                // Not using IConsole.WriteErrorLine intentionally, to keep the child's error stream intact
                 console.Error.WriteLine(args.Data);
                 buildScriptOutput.AppendLine(args.Data);
             };
@@ -256,7 +257,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
             if (!Directory.Exists(options.SourceDir))
             {
                 logger.LogError("Could not find the source directory {srcDir}", options.SourceDir);
-                console.Error.WriteLine($"Error: Could not find the source directory '{options.SourceDir}'.");
+                console.WriteErrorLine($"Could not find the source directory '{options.SourceDir}'.");
                 return false;
             }
 
@@ -264,7 +265,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
             if (string.IsNullOrEmpty(options.Language) && !string.IsNullOrEmpty(options.LanguageVersion))
             {
                 logger.LogError("Cannot use lang version without lang name");
-                console.Error.WriteLine("Cannot use language version without specifying language name also.");
+                console.WriteErrorLine("Cannot use language version without specifying language name also.");
                 return false;
             }
 
@@ -277,7 +278,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
                         "Intermediate directory {intermediateDir} cannot be a child of {srcDir}",
                         options.IntermediateDir,
                         options.SourceDir);
-                    console.Error.WriteLine(
+                    console.WriteErrorLine(
                         $"Intermediate directory '{options.IntermediateDir}' cannot be a " +
                         $"sub-directory of source directory '{options.SourceDir}'.");
                     return false;

src/BuildScriptGeneratorCli/Commands/BuildScriptCommand.cs

@@ -63,14 +63,14 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
 
             if (!Directory.Exists(options.SourceDir))
             {
-                console.Error.WriteLine($"Error: Could not find the source directory '{options.SourceDir}'.");
+                console.WriteErrorLine($"Could not find the source directory '{options.SourceDir}'.");
                 return false;
             }
 
             // Invalid to specify language version without language name
             if (string.IsNullOrEmpty(options.Language) && !string.IsNullOrEmpty(options.LanguageVersion))
             {
-                console.Error.WriteLine("Cannot use language version without specifying language name also.");
+                console.WriteErrorLine("Cannot use language version without specifying language name also.");
                 return false;
             }
 

src/BuildScriptGeneratorCli/Commands/BuildpackBuildCommand.cs

@@ -36,7 +36,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
                 if (!Directory.Exists(LayersDir))
                 {
                     logger.LogError("Could not find layers directory {layersDir}", LayersDir);
-                    console.Error.WriteLine($"Error: Could not find layers directory '{LayersDir}'.");
+                    console.WriteErrorLine($"Could not find layers directory '{LayersDir}'.");
                     result = false;
                 }
             }
@@ -47,7 +47,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
                 if (!File.Exists(PlanPath))
                 {
                     logger?.LogError("Could not find build plan file {planPath}", PlanPath);
-                    console.Error.WriteLine($"Error: Could not find build plan file '{PlanPath}'.");
+                    console.WriteErrorLine($"Could not find build plan file '{PlanPath}'.");
                     result = false;
                 }
             }
@@ -58,7 +58,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
                 if (!Directory.Exists(PlatformDir))
                 {
                     logger?.LogError("Could not find platform directory {platformDir}", PlatformDir);
-                    console.Error.WriteLine($"Error: Could not find platform directory '{PlatformDir}'.");
+                    console.WriteErrorLine($"Could not find platform directory '{PlatformDir}'.");
                     result = false;
                 }
             }

src/BuildScriptGeneratorCli/Commands/BuildpackDetectCommand.cs

@@ -43,7 +43,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
             if (!Directory.Exists(options.SourceDir))
             {
                 logger.LogError("Could not find the source directory {srcDir}", options.SourceDir);
-                console.Error.WriteLine($"Error: Could not find the source directory '{options.SourceDir}'.");
+                console.WriteErrorLine($"Could not find the source directory '{options.SourceDir}'.");
                 result = false;
             }
 
@@ -53,7 +53,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
                 if (!File.Exists(PlanPath))
                 {
                     logger?.LogError("Could not find build plan file {planPath}", PlanPath);
-                    console.Error.WriteLine($"Error: Could not find build plan file '{PlanPath}'.");
+                    console.WriteErrorLine($"Could not find build plan file '{PlanPath}'.");
                     result = false;
                 }
             }
@@ -64,7 +64,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
                 if (!Directory.Exists(PlatformDir))
                 {
                     logger?.LogError("Could not find platform directory {platformDir}", PlatformDir);
-                    console.Error.WriteLine($"Error: Could not find platform directory '{PlatformDir}'.");
+                    console.WriteErrorLine($"Could not find platform directory '{PlatformDir}'.");
                     result = false;
                 }
             }

src/BuildScriptGeneratorCli/Commands/CommandBase.cs

@@ -49,18 +49,17 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
             }
             catch (InvalidUsageException e)
             {
-                console.Error.WriteLine(e.Message);
+                console.WriteErrorLine(e.Message);
                 return ProcessConstants.ExitFailure;
             }
             catch (Exception exc)
             {
                 _serviceProvider?.GetRequiredService<ILogger<CommandBase>>()?.LogError(exc, "Exception caught");
 
-                console.Error.WriteLine(Constants.GenericErrorMessage);
+                console.WriteErrorLine(Constants.GenericErrorMessage);
                 if (ShowStackTrace)
                 {
-                    console.Error.WriteLine("Exception.ToString():");
-                    console.Error.WriteLine(exc.ToString());
+                    console.WriteErrorLine(exc.ToString());
                 }
 
                 return ProcessConstants.ExitFailure;

src/BuildScriptGeneratorCli/Commands/InstallRunTimeCommand.cs

@@ -48,7 +48,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
             var script = scriptGenerator.GenerateBashScript(Platform, options);
             if (string.IsNullOrEmpty(script))
             {
-                console.Error.WriteLine("Error: Couldn't generate startup script.");
+                console.WriteErrorLine("Couldn't generate startup script.");
                 return ProcessConstants.ExitFailure;
             }
 
@@ -61,7 +61,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
         {
             if (!Directory.Exists(InstallationPrefix))
             {
-                console.Error.WriteLine($"Error: Could not find the installation prefix directory '{InstallationPrefix}'.");
+                console.WriteErrorLine($"Could not find the installation prefix directory '{InstallationPrefix}'.");
                 return false;
             }
 

src/BuildScriptGeneratorCli/Commands/RunScriptCommand.cs

@@ -48,7 +48,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
         {
             if (string.IsNullOrWhiteSpace(PlatformName))
             {
-                console.Error.WriteLine("Platform name is required.");
+                console.WriteErrorLine("Platform name is required.");
                 return ProcessConstants.ExitFailure;
             }
 
@@ -67,7 +67,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
             var script = runScriptGenerator.GenerateBashScript(PlatformName, options);
             if (string.IsNullOrEmpty(script))
             {
-                console.Error.WriteLine("Error: Couldn't generate startup script.");
+                console.WriteErrorLine("Couldn't generate startup script.");
                 return ProcessConstants.ExitFailure;
             }
 
@@ -91,7 +91,7 @@ namespace Microsoft.Oryx.BuildScriptGeneratorCli
         {
             if (!Directory.Exists(AppDir))
             {
-                console.Error.WriteLine($"Error: Could not find the directory '{AppDir}'.");
+                console.WriteErrorLine($"Could not find the directory '{AppDir}'.");
                 return false;
             }
 

src/BuildScriptGeneratorCli/IConsoleExtensions.cs

@@ -0,0 +1,20 @@
+// --------------------------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+// --------------------------------------------------------------------------------------------
+
+using McMaster.Extensions.CommandLineUtils;
+
+namespace Microsoft.Oryx.BuildScriptGeneratorCli
+{
+    internal static class IConsoleExtensions
+    {
+        public static void WriteErrorLine(this IConsole console, string message)
+        {
+            if (!string.IsNullOrWhiteSpace(message))
+            {
+                console.Error.WriteLine("Error: " + message);
+            }
+        }
+    }
+}