PR review - Refactor checking LFS executable on PATH

- Use `in_path` to check LFS binary presence on PATH
- Fix newline in the warning message when LFS binary is not on PATH

Author: detouched

lib/overcommit/hook/pre_push/git_lfs.rb

@@ -4,10 +4,9 @@ module Overcommit::Hook::PrePush
   # @see https://git-lfs.github.com/
   class GitLfs < Base
     def run
-      result = execute(['command', '-v', 'git-lfs'])
-      unless result.success?
+      unless in_path?('git-lfs')
         return :warn, 'This repository is configured for Git LFS but \'git-lfs\' ' \
-        'was not found on your path.\nIf you no longer wish to use Git LFS, ' \
+        "was not found on your path.\nIf you no longer wish to use Git LFS, " \
         'disable this hook by removing or setting \'enabled: false\' for GitLFS ' \
         'hook in your .overcommit.yml file'
       end

spec/overcommit/hook/pre_push/git_lfs_spec.rb

@@ -8,12 +8,13 @@
   let(:result) { double('result') }
 
   before do
+    subject.stub(in_path?: true)
     subject.stub(:execute).and_return(result)
   end
 
   context 'when git-lfs is not on path' do
     before do
-      result.stub(success?: false, stderr: '')
+      subject.stub(in_path?: false)
     end
 
     it { should warn }
@@ -29,9 +30,8 @@
 
   context 'when git lfs hook exits unsuccessfully' do
     before do
-      # First for checking that git-lfs is on path, second for calling the hook itself
-      result.stub(:success?).and_return(true, false)
-      result.stub(:stderr).and_return('', 'error: failed to push some refs')
+      result.stub(success?: false)
+      result.stub(stderr: 'error: failed to push some refs')
     end
 
     it { should fail_hook }