patch: add longopts, --dry-run, add one more test

function                                             old     new   delta
patch_main                                          1110    1214    +104
static.patch_longopts                                  -      47     +47
packed_usage                                       26738   26761     +23
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/0 up/down: 174/0)             Total: 174 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

testsuite/patch.tests

@@ -7,7 +7,7 @@
 # testing "test name" "options" "expected result" "file input" "stdin"
 
 testing "patch with old_file == new_file" \
-	"patch; echo $?; cat input" \
+	'patch; echo $?; cat input' \
 "\
 patching file input
 0
@@ -15,7 +15,10 @@ qwe
 asd
 zxc
 " \
-	"qwe\nzxc\n" \
+"\
+qwe
+zxc
+" \
 "\
 --- input	Jan 01 01:01:01 2000
 +++ input	Jan 01 01:01:01 2000
@@ -26,7 +29,7 @@ zxc
 " \
 
 testing "patch with nonexistent old_file" \
-	"patch; echo $?; cat input" \
+	'patch; echo $?; cat input' \
 "\
 patching file input
 0
@@ -34,7 +37,10 @@ qwe
 asd
 zxc
 " \
-	"qwe\nzxc\n" \
+"\
+qwe
+zxc
+" \
 "\
 --- input.doesnt_exist	Jan 01 01:01:01 2000
 +++ input	Jan 01 01:01:01 2000
@@ -45,14 +51,18 @@ zxc
 " \
 
 testing "patch -R with nonexistent old_file" \
-	"patch -R; echo $?; cat input" \
+	'patch -R; echo $?; cat input' \
 "\
 patching file input
 0
 qwe
 zxc
 " \
-	"qwe\nasd\nzxc\n" \
+"\
+qwe
+asd
+zxc
+" \
 "\
 --- input.doesnt_exist	Jan 01 01:01:01 2000
 +++ input	Jan 01 01:01:01 2000
@@ -62,4 +72,29 @@ zxc
  zxc
 " \
 
+testing "patch detects already applied hunk" \
+	'patch 2>&1; echo $?; cat input' \
+"\
+patching file input
+patch: hunk #1 FAILED at 1
+patch: 1 out of 1 hunk FAILED
+1
+abc
+def
+123
+" \
+"\
+abc
+def
+123
+" \
+"\
+--- input.old	Jan 01 01:01:01 2000
++++ input	Jan 01 01:01:01 2000
+@@ -1,2 +1,3 @@
+ abc
++def
+ 123
+" \
+
 exit $FAILCOUNT