Fix acceptance test errors under RSpec 3.3

When the clearance test suite is run with RSpec 3.3, we get
`uninitialized constant RSpec::Rails::FixtureSupport`. There were some
`FixtureSupport` changes made in RSpec 3.3, but they should not impact
our acceptance tests at all.

When looking at the backtrace, I found gems from Clearance's test group
present when it should solely be gems included in our generated test
app. I switched to executing the acceptance test commands against a
clean bundler environment and everything works again.

Gemfile.lock

@@ -9,36 +9,36 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
-    actionmailer (4.2.0)
-      actionpack (= 4.2.0)
-      actionview (= 4.2.0)
-      activejob (= 4.2.0)
+    actionmailer (4.2.1)
+      actionpack (= 4.2.1)
+      actionview (= 4.2.1)
+      activejob (= 4.2.1)
       mail (~> 2.5, >= 2.5.4)
       rails-dom-testing (~> 1.0, >= 1.0.5)
-    actionpack (4.2.0)
-      actionview (= 4.2.0)
-      activesupport (= 4.2.0)
-      rack (~> 1.6.0)
+    actionpack (4.2.1)
+      actionview (= 4.2.1)
+      activesupport (= 4.2.1)
+      rack (~> 1.6)
       rack-test (~> 0.6.2)
       rails-dom-testing (~> 1.0, >= 1.0.5)
       rails-html-sanitizer (~> 1.0, >= 1.0.1)
-    actionview (4.2.0)
-      activesupport (= 4.2.0)
+    actionview (4.2.1)
+      activesupport (= 4.2.1)
       builder (~> 3.1)
       erubis (~> 2.7.0)
       rails-dom-testing (~> 1.0, >= 1.0.5)
       rails-html-sanitizer (~> 1.0, >= 1.0.1)
-    activejob (4.2.0)
-      activesupport (= 4.2.0)
+    activejob (4.2.1)
+      activesupport (= 4.2.1)
       globalid (>= 0.3.0)
-    activemodel (4.2.0)
-      activesupport (= 4.2.0)
+    activemodel (4.2.1)
+      activesupport (= 4.2.1)
       builder (~> 3.1)
-    activerecord (4.2.0)
-      activemodel (= 4.2.0)
-      activesupport (= 4.2.0)
+    activerecord (4.2.1)
+      activemodel (= 4.2.1)
+      activesupport (= 4.2.1)
       arel (~> 6.0)
-    activesupport (4.2.0)
+    activesupport (4.2.1)
       i18n (~> 0.7)
       json (~> 1.7, >= 1.7.7)
       minitest (~> 5.1)
@@ -48,7 +48,7 @@ GEM
       activesupport (>= 3.0)
       railties (>= 3.0)
       rspec-rails (>= 2.2)
-    appraisal (1.0.2)
+    appraisal (1.0.3)
       bundler
       rake
       thor (>= 0.14.0)
@@ -62,7 +62,7 @@ GEM
       rack-test (>= 0.5.4)
       xpath (~> 2.0)
     coderay (1.1.0)
-    database_cleaner (1.3.0)
+    database_cleaner (1.4.1)
     diff-lcs (1.2.5)
     email_validator (1.6.0)
       activemodel
@@ -75,15 +75,15 @@ GEM
     globalid (0.3.5)
       activesupport (>= 4.1.0)
     i18n (0.7.0)
-    json (1.8.2)
+    json (1.8.3)
     loofah (2.0.2)
       nokogiri (>= 1.5.9)
     mail (2.6.3)
       mime-types (>= 1.16, < 3)
     method_source (0.8.2)
-    mime-types (2.5)
+    mime-types (2.6.1)
     mini_portile (0.6.2)
-    minitest (5.6.1)
+    minitest (5.7.0)
     nokogiri (1.6.6.2)
       mini_portile (~> 0.6.0)
     pry (0.10.1)
@@ -93,16 +93,16 @@ GEM
     rack (1.6.1)
     rack-test (0.6.3)
       rack (>= 1.0)
-    rails (4.2.0)
-      actionmailer (= 4.2.0)
-      actionpack (= 4.2.0)
-      actionview (= 4.2.0)
-      activejob (= 4.2.0)
-      activemodel (= 4.2.0)
-      activerecord (= 4.2.0)
-      activesupport (= 4.2.0)
+    rails (4.2.1)
+      actionmailer (= 4.2.1)
+      actionpack (= 4.2.1)
+      actionview (= 4.2.1)
+      activejob (= 4.2.1)
+      activemodel (= 4.2.1)
+      activerecord (= 4.2.1)
+      activesupport (= 4.2.1)
       bundler (>= 1.3.0, < 2.0)
-      railties (= 4.2.0)
+      railties (= 4.2.1)
       sprockets-rails
     rails-deprecated_sanitizer (1.0.3)
       activesupport (>= 4.2.0.alpha)
@@ -112,33 +112,33 @@ GEM
       rails-deprecated_sanitizer (>= 1.0.1)
     rails-html-sanitizer (1.0.2)
       loofah (~> 2.0)
-    railties (4.2.0)
-      actionpack (= 4.2.0)
-      activesupport (= 4.2.0)
+    railties (4.2.1)
+      actionpack (= 4.2.1)
+      activesupport (= 4.2.1)
       rake (>= 0.8.7)
       thor (>= 0.18.1, < 2.0)
     rake (10.4.2)
-    rspec-core (3.2.0)
-      rspec-support (~> 3.2.0)
-    rspec-expectations (3.2.0)
+    rspec-core (3.3.0)
+      rspec-support (~> 3.3.0)
+    rspec-expectations (3.3.0)
       diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.2.0)
-    rspec-mocks (3.2.0)
+      rspec-support (~> 3.3.0)
+    rspec-mocks (3.3.0)
       diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.2.0)
-    rspec-rails (3.2.0)
-      actionpack (>= 3.0, <= 4.2)
-      activesupport (>= 3.0, <= 4.2)
-      railties (>= 3.0, <= 4.2)
-      rspec-core (~> 3.2.0)
-      rspec-expectations (~> 3.2.0)
-      rspec-mocks (~> 3.2.0)
-      rspec-support (~> 3.2.0)
-    rspec-support (3.2.1)
+      rspec-support (~> 3.3.0)
+    rspec-rails (3.3.0)
+      actionpack (>= 3.0, < 4.3)
+      activesupport (>= 3.0, < 4.3)
+      railties (>= 3.0, < 4.3)
+      rspec-core (~> 3.3.0)
+      rspec-expectations (~> 3.3.0)
+      rspec-mocks (~> 3.3.0)
+      rspec-support (~> 3.3.0)
+    rspec-support (3.3.0)
     shoulda-matchers (2.8.0)
       activesupport (>= 3.0.0)
     slop (3.6.0)
-    sprockets (3.1.0)
+    sprockets (3.2.0)
       rack (~> 1.0)
     sprockets-rails (2.3.1)
       actionpack (>= 3.0)
@@ -147,7 +147,7 @@ GEM
     sqlite3 (1.3.10)
     thor (0.19.1)
     thread_safe (0.3.5)
-    timecop (0.7.1)
+    timecop (0.7.4)
     tzinfo (1.2.2)
       thread_safe (~> 0.1)
     xpath (2.0.0)
@@ -169,3 +169,6 @@ DEPENDENCIES
   shoulda-matchers (~> 2.8)
   sqlite3 (~> 1.3)
   timecop (~> 0.6)
+
+BUNDLED WITH
+   1.10.2

spec/acceptance/clearance_installation_spec.rb

@@ -69,7 +69,10 @@ def successfully(command, silent = true)
       silencer = ""
     end
 
-    return_value = system("#{command} #{silencer}")
+    return_value = Bundler.with_clean_env do
+      system("#{command} #{silencer}")
+    end
+
     expect(return_value).to eq true
   end
 end