This chdir stub looks fine, I'm seeing a failure in the solaris spec though. I think the following diff will help:

```
diff --git i/spec/unit/module_tool/tar/solaris_spec.rb w/spec/unit/module_tool/tar/solaris_spec.rb
index 1ca7a6a..5641d34 100644
--- i/spec/unit/module_tool/tar/solaris_spec.rb
+++ w/spec/unit/module_tool/tar/solaris_spec.rb
@@ -8,6 +8,7 @@ describe Puppet::ModuleTool::Tar::Solaris do
   let(:destfile)   { '/the/dest/file.tar.gz' }
 
   it "unpacks a tar file" do
+    Dir.stubs(:chdir).yields
     Puppet::Util::Execution.expects(:execute).with("gtar xzf #{sourcefile} --no-same-owner -C #{destdir}")
     Puppet::Util::Execution.expects(:execute).with("find #{destdir} -type d -exec chmod 755 {} +")
     Puppet::Util::Execution.expects(:execute).with("find #{destdir} -type f -exec chmod a-wst {} +")
```