wordsplit: return single empty string on empty input in WRDSF_NOSPLIT mode

* src/wordsplit.c (wordsplit_finish): Make sure at one non-null
argument is always returned in WRDSF_NOSPLIT mode.
* tests/wordsplit.at: Add new test.

1 files changed, 11 insertions, 2 deletions

diff --git a/tests/wordsplit.at b/tests/wordsplit.at
index 631d939..e3af703 100644
--- a/tests/wordsplit.at
+++ b/tests/wordsplit.at
@@ -262,7 +262,7 @@ TOTAL: 2
 [],
 [FOO=bar BAZ=qux])
 
-TESTWSP([nosplit with expansion],[wsp-var-nosplit],[nosplit],
+TESTWSP([nosplit with variable expansion],[wsp-var-nosplit],[nosplit],
 [a $FOO test],
 [NF: 1
 0: "a variable expansion test\n"
@@ -271,7 +271,7 @@ TOTAL: 1
 [],
 [FOO="variable expansion"])
 
-TESTWSP([nosplit without expansion],[],[nosplit novar],
+TESTWSP([nosplit without variable expansion],[],[nosplit novar],
 [a $FOO test],
 [NF: 1
 0: "a $FOO test\n"
@@ -280,6 +280,15 @@ TOTAL: 1
 [],
 [FOO="variable expansion"])
 
+TESTWSP([nosplit: empty expansion],[],[nosplit trimnl],
+[$FOO],
+[NF: 1
+0: ""
+TOTAL: 1
+],
+[],
+[FOO=""])
+
 TESTWSP([default value (defined)],[],[],
 [${FOO:-bar}],
 [NF: 1