tests: add test coverage for uci export with -P option.

 - With "uci -P xxx/ export", changes in "xxx/" should be applied last.
 - With "uci -p xxx/ commit", changes in "xxx/" should be applied before
   ctx->savedir.

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

test/references/cli.options.delta.export.result

@@ -0,0 +1,5 @@
+package delta
+
+config sectype 'sec0'
+	list li0 '0'
+	list li0 '1'

test/tests.d/090_cli_options

@@ -1,6 +1,7 @@
 test_add_delta() {
 	local new_savedir="$TMP_DIR/new_savedir"
 	local config_delta="$CONFIG_DIR/delta"
+	local cmdoutput
 
 	# add normal changes
 	touch "$config_delta"
@@ -16,11 +17,18 @@ test_add_delta() {
 	assertEquals "delta.sec0='sectype'
 delta.sec0.li0+='0'" "$($UCI changes)"
 
-	# check combined changes.  order matters here.
+	# check combined changes.  Order matters here.
+	cmdoutput="$($UCI -P "$new_savedir" changes)"
+	assertTrue "$?"
 	assertEquals "delta.sec0='sectype'
-delta.sec0.li0+='1'
+delta.sec0.li0+='0'
 delta.sec0='sectype'
-delta.sec0.li0+='0'" "$($UCI -P "$new_savedir" changes)"
+delta.sec0.li0+='1'" "$cmdoutput"
+
+	# check combined export.  Order matters here.
+	cmdoutput="$($UCI -P "$new_savedir" export)"
+	assertTrue "$?"
+	assertEquals "$(cat $REF_DIR/cli.options.delta.export.result)" "$cmdoutput"
 
 	# check CLI_FLAG_NOCOMMIT with -P option.
 	$UCI -P "$new_savedir" commit
@@ -30,7 +38,7 @@ delta.sec0.li0+='0'" "$($UCI -P "$new_savedir" changes)"
 	# check normal commit.
 	$UCI -p "$new_savedir" commit
 	assertTrue "$?"
-	assertSameFile "$REF_DIR/options.delta.result" "$config_delta"
+	assertSameFile "$REF_DIR/cli.options.delta.commit.result" "$config_delta"
 
 	rm -rf "$new_savedir"
 	rm -f "$config_delta"