Add test: Add parts of a file to another zip file.

regress/Makefile.am

diff --git a/regress/Makefile.am b/regress/Makefile.am
index 71df741..9cbd15d 100644
--- a/regress/Makefile.am
+++ b/regress/Makefile.am
@@ -21,6 +21,8 @@
 	broken.zip \
 	encrypt.zip \
 	fileorder.zip \
+	firstsecond.zip \
+	firstsecond-split.zip \
 	manyfiles.zip \
 	rename_ok.zip \
 	test.zip \
@@ -56,6 +58,7 @@
 	add_from_file_twice_duplicate.test \
 	add_from_filep.test \
 	add_from_zip_deflated.test \
+	add_from_zip_partial.test \
 	add_from_zip_stored.test \
 	delete_add_same.test \
 	delete_invalid.test \

regress/add_from_zip_partial.test

diff --git a/regress/add_from_zip_partial.test b/regress/add_from_zip_partial.test
new file mode 100644
index 0000000..a166308
--- /dev/null
+++ b/regress/add_from_zip_partial.test
@@ -0,0 +1,6 @@
+# add parts of a file from zip to zip
+program modify
+return 0
+args testfile.zip   add_from_zip first firstsecond.zzip 0 0 9   add_from_zip second firstsecond.zzip 0 9 -1
+file firstsecond.zzip firstsecond.zip firstsecond.zip
+file-new testfile.zip firstsecondsplit.zip

regress/firstsecond.zip

diff --git a/regress/firstsecond.zip b/regress/firstsecond.zip
new file mode 100644
index 0000000..fca0b52
--- /dev/null
+++ b/regress/firstsecond.zip
Binary files differ

regress/firstsecondsplit.zip

diff --git a/regress/firstsecondsplit.zip b/regress/firstsecondsplit.zip
new file mode 100644
index 0000000..35f0684
--- /dev/null
+++ b/regress/firstsecondsplit.zip
Binary files differ