[Executable] Handle when $PATH is not set

CHANGELOG.md

@@ -32,6 +32,9 @@ To install release candidates run `[sudo] gem install cocoapods --pre`
   `Copy Pods Resources` build phase.  
   [seaders](https://github.com/seaders) [#4940](https://github.com/CocoaPods/CocoaPods/issues/4940)
 
+* Handle when `$PATH` isn't set.  
+  [Samuel Giddins](https://github.com/segiddins)
+
 
 ## 1.0.0.beta.4 (2016-02-24)
 

lib/cocoapods/executable.rb

@@ -46,8 +46,7 @@ module Pod
     # @return [String] the output of the command (STDOUT and STDERR).
     #
     def self.execute_command(executable, command, raise_on_failure = true)
-      bin = which(executable)
-      raise Informative, "Unable to locate the executable `#{executable}`" unless bin
+      bin = which!(executable)
 
       command = command.map(&:to_s)
       full_command = "#{bin} #{command.join(' ')}"
@@ -87,7 +86,10 @@ module Pod
     #
     def self.which(program)
       program = program.to_s
-      ENV['PATH'].split(File::PATH_SEPARATOR).each do |path|
+      paths = ENV.fetch('PATH') { '' }.split(File::PATH_SEPARATOR)
+      paths.unshift('./')
+      paths.uniq!
+      paths.each do |path|
         bin = File.expand_path(program, path)
         if File.file?(bin) && File.executable?(bin)
           return bin
@@ -96,6 +98,20 @@ module Pod
       nil
     end
 
+    # Returns the absolute path to the binary with the given name on the current
+    # `PATH`, or raises if none is found.
+    #
+    # @param  [String] program
+    #         The name of the program being searched for.
+    #
+    # @return [String] The absolute path to the given program.
+    #
+    def self.which!(program)
+      which(program).tap do |bin|
+        raise Informative, "Unable to locate the executable `#{executable}`" unless bin
+      end
+    end
+
     # Runs the given command, capturing the desired output.
     #
     # @param  [String] bin
@@ -114,8 +130,7 @@ module Pod
     #         running the command.
     #
     def self.capture_command(executable, command, capture: :merge)
-      bin = which(executable)
-      raise Informative, "Unable to locate the executable `#{executable}`" unless bin
+      bin = which!(executable)
 
       require 'open3'
       command = command.map(&:to_s)