Build integration specs with Xcode 8.3.2

CONTRIBUTING.md

@@ -49,7 +49,7 @@ git push
 You'll need push access to the integration specs repo to do this. You can
 request access from one of the maintainers when filing your PR.
 
-You must have Xcode 8.2 installed to build the integration specs.
+You must have Xcode 8.3.2 installed to build the integration specs.
 
 ## Making changes to SourceKitten
 

circle.yml

@@ -1,6 +1,6 @@
 machine:
   xcode:
-    version: "8.2"
+    version: "8.3.2"
 
 checkout:
   post:

lib/jazzy/config.rb

@@ -162,6 +162,7 @@ def expand_path(path)
       command_line: '--swift-version VERSION',
       default: nil,
       parse: ->(v) do
+        return nil if v.empty?
         raise 'jazzy only supports Swift 2.0 or later.' if v.to_f < 2
         v
       end

spec/integration_spec.rb

@@ -203,7 +203,10 @@
 
     describe 'Creates Siesta docs' do
       behaves_like cli_spec 'document_siesta',
-                            '--output api-docs' # Siesta already has Docs/
+                            # Siesta already has Docs/
+                            '--output api-docs',
+                            # Use default Swift rather than the specified 3.0.2
+                            '--swift-version='
     end
 
     describe 'Creates docs for Swift project with a variety of contents' do