Object returned from GitVersion not consistent - gitversion

Question

Is it normal that the object returned by the GitVersion alias is different if I specify 'OutputType' vs omitting this setting?
If I specify the output type, the properties of the returned object are all 'null' but when I omit the setting, the properties are set to expected values
For example:
Task("Version")
.Does(() =>
{
var versionInfo = GitVersion(new GitVersionSettings()
{
UpdateAssemblyInfo = true,
OutputType = GitVersionOutput.BuildServer
});
Information("MajorMinorPatch: {0}", versionInfo.MajorMinorPatch);
Information("FullSemVer: {0}", versionInfo.FullSemVer);
Information("InformationalVersion: {0}", versionInfo.InformationalVersion);
Information("LegacySemVer: {0}", versionInfo.LegacySemVer);
Information("Nuget v1 version: {0}", versionInfo.NuGetVersion);
Information("Nuget v2 version: {0}", versionInfo.NuGetVersionV2);
});
The output is:
MajorMinorPatch: [NULL]
FullSemVer: [NULL]
InformationalVersion: [NULL]
LegacySemVer: [NULL]
Nuget v1 version: [NULL]
Nuget v2 version: [NULL]
If I change my task like so:
Task("Version")
.Does(() =>
{
var versionInfo = GitVersion(new GitVersionSettings()
{
UpdateAssemblyInfo = false
});
Information("MajorMinorPatch: {0}", versionInfo.MajorMinorPatch);
Information("FullSemVer: {0}", versionInfo.FullSemVer);
Information("InformationalVersion: {0}", versionInfo.InformationalVersion);
Information("LegacySemVer: {0}", versionInfo.LegacySemVer);
Information("Nuget v1 version: {0}", versionInfo.NuGetVersion);
Information("Nuget v2 version: {0}", versionInfo.NuGetVersionV2);
});
The output is:
MajorMinorPatch: 0.1.0
FullSemVer: 0.1.0+1
InformationalVersion: 0.1.0+1.Branch.master.Sha.5b2
LegacySemVer: 0.1.0
Nuget v1 version: 0.1.0
Nuget v2 version: 0.1.0

Answer 1

This is "by-design".
https://github.com/cake-build/cake/blob/develop/src/Cake.Common/Tools/GitVersion/GitVersionRunner.cs#L71
GitVersion has a default output type of JSON, which means that the JSON output which contains all the asserted version numbers is available for inspection. At this point, Cake collects this JSON output, combines them into a GitVersion object, and returns that to the Cake script.
When you use OutputType = GitVersionOutput.BuildServer there is no JSON output. Instead, GitVersion works with the Build Server that it is running on, whether that is TeamCity, AppVeyor, or whatever, and makes the asserted version numbers available via another mechanism. i.e. either via setting environment variables, or using service messages to tell the build server about this. As a result, there is nothing really for Cake to consume to create the GitVersion object for returning.
The typical way around this would be to first run GitVersion with OutputType = GitVersionOutput.BuildServer and then immediately run it again, and use the returned variables. This is actually what we do within our own Cake script:
https://github.com/cake-build/cake/blob/develop/build/version.cake#L38
Running this a second time should actually be very quick, as GitVersion actually caches the result of the first run. There might actually be something that we can do in Cake to read this cached output, and use that as the output of the call. Would you be able to raise this as an issue here so we can track it?