a few more minor tests

acedoc_test.go

@@ -285,6 +285,7 @@ func TestDelta2(t *testing.T) {
 	}
 
 }
+
 func TestDelta(t *testing.T) {
 	type c struct {
 		name   string
@@ -333,8 +334,20 @@ func TestDelta(t *testing.T) {
 		{"remove part",
 			"aa", "a", Remove(0, 0, "a")},
 
+		{"remove other part",
+			"aa", "a", Remove(0, 1, "a")},
+
 		{"remove across line",
 			"a\nb", "a", Remove(0, 1, "\nb")},
+
+		{"remove across two lines",
+			"a\nb\nc", "ac", Remove(0, 1, "\nb\n")},
+
+		{"remove all across line",
+			"a\nb", "", Remove(0, 0, "a\nb")},
+
+		{"remove all across two lines",
+			"a\nb\nc", "", Remove(0, 0, "a\nb\nc")},
 	}
 
 	for _, c := range cases {