Try fix for failing config testjdm/config-workstation-spec

We keep seeing this randomly
```
1) Chef::WorkstationConfigLoader loading the config file when the config file exists and raises a ruby exception during evaluation raises a ConfigurationError
   Failure/Error: expect { config_loader.load }.to raise_error(Chef::Exceptions::ConfigurationError)
     expected Chef::Exceptions::ConfigurationError, got #<Errno::ENOENT: No such file or directory @ rb_sysopen - /tmp/Chef-WorkstationConfigLoader-rspec-test20150707-35300-f9yfb6> with backtrace:
       # ./lib/chef/workstation_config_loader.rb:164:in `readlines'
       # ./lib/chef/workstation_config_loader.rb:164:in `highlight_config_error'
       # ./lib/chef/workstation_config_loader.rb:156:in `rescue in read_config'
       # ./lib/chef/workstation_config_loader.rb:137:in `read_config'
       # ./lib/chef/workstation_config_loader.rb:72:in `load'
       # ./spec/unit/workstation_config_loader_spec.rb:275:in `block (6 levels) in <top (required)>'
       # ./spec/unit/workstation_config_loader_spec.rb:275:in `block (5 levels) in <top (required)>'
   # ./spec/unit/workstation_config_loader_spec.rb:275:in `block (5 levels) in <top (required)>'
```

I think the issue is that the tempfile gets GC'd, and when it gets GC'd, it deletes the file.
If it is cleaned up before it is used, then the test fails.

1 files changed, 10 insertions, 5 deletions

diff --git a/chef-config/spec/unit/workstation_config_loader_spec.rb b/chef-config/spec/unit/workstation_config_loader_spec.rb
index f247d1cac2..9f24a4f11b 100644
--- a/chef-config/spec/unit/workstation_config_loader_spec.rb
+++ b/chef-config/spec/unit/workstation_config_loader_spec.rb
@@ -236,12 +236,17 @@ RSpec.describe ChefConfig::WorkstationConfigLoader do
 
       let(:config_content) { "" }
 
+      # We need to keep a reference to the tempfile because while #close does
+      # not unlink the file, the object being GC'd will.
+      let(:tempfile) do
+        Tempfile.new("Chef-WorkstationConfigLoader-rspec-test").tap do |t|
+          t.print(config_content)
+          t.close
+        end
+      end
+
       let(:explicit_config_location) do
-        # could use described_class, but remove all ':' from the path if so.
-        t = Tempfile.new("Chef-WorkstationConfigLoader-rspec-test")
-        t.print(config_content)
-        t.close
-        t.path
+        tempfile.path
       end
 
       after { File.unlink(explicit_config_location) if File.exist?(explicit_config_location) }