Retrieve/use absolute path of executable within Beautifier::run

See #375. Will help with debugging Windows CI

package.json

@@ -79,6 +79,7 @@
     "tidy-markdown": "^0.3.2",
     "typescript-formatter": "~0.3.2",
     "underscore-plus": "^1.6.6",
+    "which": "^1.1.1",
     "winston": "^1.0.0",
     "yaml-front-matter": "^3.2.3"
   },

src/beautifiers/beautifier.coffee

@@ -5,11 +5,12 @@ temp = require("temp").track()
 exec = require("child_process").exec
 spawn = require("child_process").spawn
 readFile = Promise.promisify(fs.readFile)
+which = require('which')
 
 module.exports = class Beautifier
 
     ###
-
+    Promise
     ###
     Promise: Promise
 
@@ -132,25 +133,46 @@ module.exports = class Beautifier
                     resolve(environment)
             )
 
+    ###
+    Like the unix which utility.
+
+    Finds the first instance of a specified executable in the PATH environment variable.
+    Does not cache the results,
+    so hash -r is not needed when the PATH changes.
+    See https://github.com/isaacs/node-which
+    ###
+    which: (exe, options = {}) ->
+        # Get PATH and other environment variables
+        @getShellEnvironment()
+        .then((env) ->
+            new Promise((resolve, reject) ->
+                options.path ?= env.PATH
+                which(exe, options, (err, path) ->
+                    resolve(exe) if err
+                    resolve(path)
+                )
+            )
+        )
+
     ###
     Run command-line interface command
     ###
     run: (executable, args, {ignoreReturnCode, help} = {}) ->
-        # Resolve executable
-        Promise.resolve(executable)
-        .then((exe) =>
         # Flatten args first
         args = _.flatten(args)
-            # Resolve all args
-            Promise.all(args)
-            .then((args) =>
+        # Resolve executable and all args
+        Promise.all([executable, Promise.all(args)])
+        .then(([exeName, args]) =>
+            @debug('exeName, args:', exeName, args)
             return new Promise((resolve, reject) =>
                 # Remove undefined/null values
                 args = _.without(args, undefined)
                 args = _.without(args, null)
                 # Get PATH and other environment variables
-                    @getShellEnvironment()
-                    .then((env) =>
+                Promise.all([@getShellEnvironment(), @which(exeName)])
+                .then(([env, exePath]) =>
+                    @debug('exePath, env:', exePath, env)
+                    exe = exePath ? exeName
                     # Spawn command
                     stdout = ""
                     stderr = ""
@@ -162,7 +184,9 @@ module.exports = class Beautifier
                     # add a 'data' event listener for the spawn instance
                     cmd.stdout.on('data', (data) -> stdout += data )
                     cmd.stderr.on('data', (data) -> stderr += data )
-                        # when the spawn child process exits, check if there were any errors and close the writeable stream
+                    # when the spawn child process exits,
+                    # check if there were any errors and
+                    # close the writeable stream
                     cmd.on('exit', (returnCode) =>
                         @debug('spawn done', returnCode, stderr, stdout)
                         # If return code is not 0 then error occured
@@ -173,12 +197,15 @@ module.exports = class Beautifier
                     )
                     cmd.on('error', (err) =>
                         @debug('error', err)
-                            # Check if error is ENOENT (command could not be found)
+                        # Check if error is ENOENT
+                        # (command could not be found)
                         if err.code is 'ENOENT' or err.errno is 'ENOENT'
                             # Create new improved error
-                                # notify user that it may not be installed or in path
-                                message = "Could not find '#{exe}'. The program may not be installed."
-                                er = new Error(message) # +(if help then "\n\n#{help}" else "")
+                            # notify user that it may not be
+                            # installed or in path
+                            message = "Could not find '#{exe}'. \
+                                The program may not be installed."
+                            er = new Error(message)
                             if help?
                                 if typeof help is "object"
                                     helpStr = "See #{help.link} for program installation instructions.\n"
@@ -201,7 +228,7 @@ module.exports = class Beautifier
                 )
             )
         )
-        )
+
 
     ###
     Logger instance