Add method "prepend_path" to control PATH when running commands.

bin/cmdtest.rb

@@ -160,8 +160,18 @@ module Cmdtest
       end
     end
 
+    def prepend_path_dirs(path_dirs)
+      full_path_dirs = path_dirs.map {|dir| File.expand_path(dir, @orig_cwd) }
+      new_env_path = (full_path_dirs + [@orig_envpath]).join(Config::CONFIG["PATH_SEPARATOR"])
+      if new_env_path != ENV["PATH"]
+        ENV["PATH"] = new_env_path
+      end
+    end
+
     def run
+      @orig_cwd = Dir.pwd
       ENV["PATH"] = Dir.pwd + Config::CONFIG["PATH_SEPARATOR"] + ENV["PATH"]
+      @orig_envpath = ENV["PATH"]
       @n_assert_failures  = 0
       @n_assert_errors    = 0
       @n_assert_successes = 0

lib/cmdtest/testcase.rb

@@ -68,6 +68,7 @@ module Cmdtest
       @_work_dir = Workdir.new(runner)
       @_in_cmd = false
       @_comment_str = nil
+      @_prepend_path_dirs = []
     end
 
     #------------------------------
@@ -131,6 +132,15 @@ module Cmdtest
       end
     end
 
+    #------------------------------
+    # Prepend the given directory to the PATH before running commands.
+    # The path is evaluated realtive to the current directory when 'cmdtest'
+    # was started.
+
+    def prepend_path(dir)
+      @_prepend_path_dirs.unshift(dir)
+    end
+
     #==============================
 
     # Used in methods invoked from the "cmd" do-block, in methods that
@@ -470,6 +480,7 @@ module Cmdtest
 
       @_runner.notify("cmdline", @_cmdline, @_comment_str)
       @_comment_str = nil
+      @_runner.prepend_path_dirs(@_prepend_path_dirs)
       @_effects = @_work_dir.run_cmd(@_cmdline)
 
       @_checked_status = false