GH-2127 - allow only buildserver

Author: arturcic

src/GitVersionCore/Arguments.cs

@@ -8,10 +8,6 @@ namespace GitVersion
 {
     public class Arguments
     {
-        public Arguments()
-        {
-            Output.Add(OutputType.Json);
-        }
         public AuthenticationInfo Authentication;
 
         public Config OverrideConfig;

src/GitVersionExe.Tests/ArgumentParserTests.cs

@@ -143,13 +143,31 @@ public void OutputJsonCanBeParsed()
         {
             var arguments = argumentParser.ParseArguments("targetDirectoryPath -output json");
             arguments.Output.ShouldContain(OutputType.Json);
+            arguments.Output.ShouldNotContain(OutputType.BuildServer);
+        }
+
+        [Test]
+        public void MultipleOutputJsonCanBeParsed()
+        {
+            var arguments = argumentParser.ParseArguments("targetDirectoryPath -output json -output json");
+            arguments.Output.ShouldContain(OutputType.Json);
+            arguments.Output.ShouldNotContain(OutputType.BuildServer);
         }
 
         [Test]
         public void OutputBuildserverCanBeParsed()
         {
             var arguments = argumentParser.ParseArguments("targetDirectoryPath -output buildserver");
             arguments.Output.ShouldContain(OutputType.BuildServer);
+            arguments.Output.ShouldNotContain(OutputType.Json);
+        }
+
+        [Test]
+        public void MultipleOutputBuildserverCanBeParsed()
+        {
+            var arguments = argumentParser.ParseArguments("targetDirectoryPath -output buildserver -output buildserver");
+            arguments.Output.ShouldContain(OutputType.BuildServer);
+            arguments.Output.ShouldNotContain(OutputType.Json);
         }
 
         [Test]

src/GitVersionExe/ArgumentParser.cs

@@ -264,12 +264,16 @@ public Arguments ParseArguments(string[] commandLineArguments)
 
                 if (name.IsSwitch("output"))
                 {
-                    if (!Enum.TryParse(value, true, out OutputType outputType))
+                    foreach (var v in values)
                     {
-                        throw new WarningException($"Value '{value}' cannot be parsed as output type, please use 'json' or 'buildserver'");
+                        if (!Enum.TryParse(v, true, out OutputType outputType))
+                        {
+                            throw new WarningException($"Value '{value}' cannot be parsed as output type, please use 'json' or 'buildserver'");
+                        }
+
+                        arguments.Output.Add(outputType);
                     }
 
-                    arguments.Output.Add(outputType);
                     continue;
                 }
 
@@ -396,6 +400,11 @@ public Arguments ParseArguments(string[] commandLineArguments)
                 throw new WarningException(couldNotParseMessage);
             }
 
+            if (arguments.Output.Count == 0)
+            {
+                arguments.Output.Add(OutputType.Json);
+            }
+
             if (arguments.TargetPath == null)
             {
                 // If the first argument is a switch, it should already have been consumed in the above loop,