(build) show error message in case the docker artifacts are failing

Author: arturcic

build/artifacts-test.cake

@@ -19,8 +19,11 @@ Task("Artifacts-DotnetTool-Test")
 
     foreach(var dockerImage in parameters.Docker.Images)
     {
-        var cmd = $"dotnet tool install GitVersion.Tool --version {version} --tool-path {rootPrefix}/gitversion --add-source {rootPrefix}/nuget | out-null; ";
+        var cmd = $"$result = dotnet tool install GitVersion.Tool --version {version} --tool-path {rootPrefix}/gitversion --add-source {rootPrefix}/nuget | out-null; ";
+        cmd += "if($LASTEXITCODE -eq 0) { ";
         cmd += $"{rootPrefix}/gitversion/dotnet-gitversion {rootPrefix}/repo /showvariable FullSemver;";
+        cmd += "} else { echo $result }";
+
 
         DockerTestArtifact(dockerImage, parameters, cmd);
     }
@@ -38,8 +41,10 @@ Task("Artifacts-MsBuild-Test")
     foreach(var dockerImage in parameters.Docker.Images)
     {
         var (os, distro, targetframework) = dockerImage;
-        var cmd = $"dotnet build {rootPrefix}/repo/test --source {rootPrefix}/nuget --source https://api.nuget.org/v3/index.json -p:GitVersionTaskVersion={version} -p:TargetFramework={targetframework} | out-null; ";
+        var cmd = $"$result = dotnet build {rootPrefix}/repo/test --source {rootPrefix}/nuget --source https://api.nuget.org/v3/index.json -p:GitVersionTaskVersion={version} -p:TargetFramework={targetframework} *>&1; ";
+        cmd += "if($LASTEXITCODE -eq 0) { ";
         cmd += $"dotnet {rootPrefix}/repo/test/build/corefx/{targetframework}/TestRepo.dll;";
+        cmd += "} else { echo $result }";
 
         DockerTestArtifact(dockerImage, parameters, cmd);
     }