Output error message when test file/dir not found

Previously, if a test file or directory specified on the command-line
is not found, the test file loader would silently fail without reporting
an error. Hence, leading the user to think all requested tests were run,
when, in fact, either an entire test file or directory was skipped. This
updates the test file loader to report an error in the event a requested
file or directory is not found.

busted/languages/en.lua

@@ -26,6 +26,7 @@ s:set('output.success_single', 'success')
 s:set('output.seconds', 'seconds')
 
 s:set('output.no_test_files_match', 'No test files found matching Lua pattern: %s')
+s:set('output.file_not_found', 'Cannot find file or directory: %s')
 
 -- definitions following are not used within the 'say' namespace
 return {

busted/modules/test_file_loader.lua

@@ -43,6 +43,7 @@ return function(busted, loaders)
         end
       end)
     else
+      busted.publish({ 'error' }, {}, nil, s('output.file_not_found'):format(rootFile), {})
       fileList = {}
     end
 

spec/cl_spec.lua

@@ -454,6 +454,20 @@ describe('Tests error messages through the command line', function()
     assert.is_equal(expectedMsg, errmsg)
   end)
 
+  it('when test file not found', function()
+    local _, _, result = executeBusted('--output=plainTerminal does_not_exist.lua')
+    local errmsg = result:match('Error %-> (.-)\n')
+    local expected = 'Cannot find file or directory: does_not_exist.lua'
+    assert.is_equal(expected, errmsg)
+  end)
+
+  it('when test directory not found', function()
+    local _, _, result = executeBusted('--output=plainTerminal does_not_exist')
+    local errmsg = result:match('Error %-> (.-)\n')
+    local expected = 'Cannot find file or directory: does_not_exist'
+    assert.is_equal(expected, errmsg)
+  end)
+
   it('when no test files matching Lua pattern', function()
     local _, _, result = executeBusted('--output=plainTerminal --pattern=this_filename_does_simply_not_exist$')
     local errmsg = result:match('Error %-> (.-)\n')