Added PATCH.LUA unit test for multiple files.

Author: Lethja

test/PATCH/case21/a.txt

@@ -0,0 +1 @@
+../case03/a.txt

test/PATCH/case21/b.txt

@@ -0,0 +1 @@
+../case03/b.txt

test/PATCH/case21/c.txt

@@ -0,0 +1 @@
+../case20/a.txt

test/PATCH/case21/d.txt

@@ -0,0 +1 @@
+../case20/b.txt

test/PATCH/test.sh

@@ -9,18 +9,28 @@ test_case() {
   cp "case$1"/* result
   cd "result"
   diff -u a.txt b.txt > "diff"
+  if [ -f "c.txt" ] && [ -f "d.txt" ]; then diff -u c.txt d.txt >> "diff"; fi
   $INTERP $SCRIPT diff
-  if { set +e; cmp -s a.txt b.txt; }; then
-    printf "\tCASE %s: PASS\n" "$1"
+  if [ -f "c.txt" ] && [ -f "d.txt" ]; then
+    if { set +e; cmp -s a.txt b.txt; } && { set +e; cmp -s c.txt d.txt; }; then
+      printf "\tCASE %s: PASS\n" "$1"
+    else
+      printf "\tCASE %s: FAIL\n" "$1"
+      FAIL=$((FAIL + 1))
+    fi
   else
-    printf "\tCASE %s: FAIL\n" "$1"
-    FAIL=$((FAIL + 1))
+    if { set +e; cmp -s a.txt b.txt; }; then
+      printf "\tCASE %s: PASS\n" "$1"
+    else
+      printf "\tCASE %s: FAIL\n" "$1"
+      FAIL=$((FAIL + 1))
+    fi
   fi
   cd ..
   rm -R result
 }
 echo "PATCH:"
-for i in $(seq -w 1 20); do test_case "$i"; done
+for i in $(seq -w 1 21); do test_case "$i"; done
 echo ""
 if [ $FAIL -gt 0 ]; then echo "PATCH: $FAIL FAIL"; exit 1; fi
 echo "PATCH: ALL PASS"