Add tests for the diff.ignoreSubmodules config option

diff --git a/t/README b/t/README
index b906ceb4766a283ae6b22bd037f9e1619feb12d1..0d1183c3e69904e9e3543d757f14f10c629e199b 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 ...
@@ -451,8 +451,10 @@ library for your script to use.
  - test_must_fail <git-command>
 
    Run a git command and ensure it fails in a controlled way.  Use
-   this instead of "! <git-command>" to fail when git commands
-   segfault.
+   this instead of "! <git-command>".  When git-command dies due to a
+   segfault, test_must_fail diagnoses it as an error; "! <git-command>"
+   treats it as just another expected failure, which would let such a
+   bug go unnoticed.
 
  - test_might_fail <git-command>