tests: make test_must_fail more verbose

diff --git a/t/README b/t/README
index a5901424388b9cfb525b7bdbfd6d5afda3c9e014..410499a09645634349d7685e728228f238021c34 100644 (file)
--- a/t/README
+++ b/t/README
@@ -259,11 +259,11 @@ Do:
        test ...
 
    That way all of the commands in your tests will succeed or fail. If
-   you must ignore the return value of something (e.g. the return
-   value of export is unportable) it's best to indicate so explicitly
-   with a semicolon:
+   you must ignore the return value of something (e.g., the return
+   after unsetting a variable that was already unset is unportable) it's
+   best to indicate so explicitly with a semicolon:
 
-       export HLAGH;
+       unset HLAGH;
        git merge hla &&
        git push gh &&
        test ...
@@ -467,6 +467,13 @@ library for your script to use.
    <expected> file.  This behaves like "cmp" but produces more
    helpful output when the test is run with "-v" option.
 
+ - test_path_is_file <file> [<diagnosis>]
+   test_path_is_dir <dir> [<diagnosis>]
+   test_path_is_missing <path> [<diagnosis>]
+
+   Check whether a file/directory exists or doesn't. <diagnosis> will
+   be displayed if the test fails.
+
  - test_when_finished <script>
 
    Prepend <script> to a list of commands to run to clean up