Log standard output/error output in debug mode

In order to make debugging hook runs easier, include output from the
standard output/error streams when the OVERCOMMIT_DEBUG environment
variable is set.

Author: sds

CHANGELOG.md

@@ -16,6 +16,8 @@
 * Add `rewritten_commits` helper to `PostRewrite` hooks
 * Add `gemfile` option to configuration file which allows a `Gemfile` to be
   loaded by Bundler to enforce particular gem versions during hook runs
+* Add support for `OVERCOMMIT_DEBUG` environment variable which toggles the
+  display of additional verbose output from executed commands
 
 ## 0.26.0
 

lib/overcommit/cli.rb

@@ -9,6 +9,8 @@ def initialize(arguments, input, logger)
       @input     = input
       @log       = logger
       @options   = {}
+
+      Overcommit::Utils.log = logger
     end
 
     def run

lib/overcommit/utils.rb

@@ -25,6 +25,9 @@ class Version < Gem::Version
     end
 
     class << self
+      # @return [Overcommit::Logger] logger with which to send debug output
+      attr_accessor :log
+
       def script_path(script)
         File.join(Overcommit::HOME, 'libexec', script)
       end
@@ -162,11 +165,20 @@ def execute(args, splittable_args = nil)
                 'Cannot pipe commands with the `execute` helper'
         end
 
-        if splittable_args
-          Overcommit::CommandSplitter.execute(args, splittable_args)
-        else
-          Overcommit::Subprocess.spawn(args)
-        end
+        result =
+          if splittable_args
+            log.debug(args.join(' ') + " ... (#{splittable_args.length} splittable args)")
+            Overcommit::CommandSplitter.execute(args, splittable_args)
+          else
+            log.debug(args.join(' '))
+            Overcommit::Subprocess.spawn(args)
+          end
+
+        log.debug("EXIT STATUS: #{result.status}")
+        log.debug("STDOUT: #{result.stdout.inspect}")
+        log.debug("STDERR: #{result.stderr.inspect}")
+
+        result
       end
 
       # Execute a command in a subprocess, returning immediately.
@@ -182,6 +194,7 @@ def execute_in_background(args)
                 'Cannot pipe commands with the `execute_in_background` helper'
         end
 
+        log.debug("Spawning background task: #{args.join(' ')}")
         Subprocess.spawn_detached(args)
       end
 

template-dir/hooks/overcommit-hook

@@ -50,6 +50,7 @@ end
 
 begin
   logger = Overcommit::Logger.new(STDOUT)
+  Overcommit::Utils.log = logger
 
   # Ensure master hook is up-to-date
   installer = Overcommit::Installer.new(logger)