Fix ProtectedBranches specs to not use stub for config

This also pulls up some duplicate stubs to DRY up the tests.

Author: sds

spec/overcommit/hook/pre_push/protected_branches_spec.rb

@@ -2,7 +2,14 @@
 require 'overcommit/hook_context/pre_push'
 
 describe Overcommit::Hook::PrePush::ProtectedBranches do
-  let(:config)  { Overcommit::ConfigurationLoader.default_configuration }
+  let(:hook_config) { {} }
+  let(:config) do
+    Overcommit::ConfigurationLoader.default_configuration.merge(
+      Overcommit::Configuration.new(
+        'PrePush' => { 'ProtectedBranches' => hook_config }
+      )
+    )
+  end
   let(:context) { double('context') }
   subject { described_class.new(config, context) }
 
@@ -39,38 +46,36 @@
 
   shared_examples_for 'protected branch' do
     context 'when push is not destructive' do
+      before do
+        pushed_ref.stub(:destructive?).and_return(false)
+      end
+
       context 'and destructive_only set to false' do
-        before do
-          pushed_ref.stub(:destructive?).and_return(false)
-          subject.stub(destructive_only?: false)
-        end
+        let(:hook_config) { { 'destructive_only' => false } }
 
         it { should fail_hook }
       end
 
       context 'and destructive_only set to true' do
-        before do
-          subject.stub(destructive_only?: true)
-          pushed_ref.stub(:destructive?).and_return(false)
-        end
+        let(:hook_config) { { 'destructive_only' => true } }
 
         it { should pass }
       end
     end
 
     context 'when push is destructive' do
+      before do
+        pushed_ref.stub(:destructive?).and_return(true)
+      end
+
       context 'when destructive_only is set to true' do
-        before do
-          pushed_ref.stub(:destructive?).and_return(true)
-        end
+        let(:hook_config) { { 'destructive_only' => true } }
 
         it { should fail_hook }
       end
 
       context 'when destructive_only is set to false' do
-        before do
-          subject.stub(:allow_non_destructive?).and_return(true)
-        end
+        let(:hook_config) { { 'destructive_only' => false } }
 
         it { should fail_hook }
       end