diff --git a/re_test.go b/re_test.go
index ef8c2d5..5d205c4 100644
--- a/re_test.go
+++ b/re_test.go
@@ -156,6 +156,28 @@ var reTests = []struct {
 	{"(?<=f)f+(?=f)", "fffffa", []Group{{1, 4}}},
 }
 
+var groupTests = []struct {
+	re     string
+	str    string
+	result []Match
+}{
+	{"(a)(b)", "ab", []Match{[]Group{{0, 2}, {0, 1}, {1, 2}}}},
+	{"((a))(b)", "ab", []Match{[]Group{{0, 2}, {0, 1}, {0, 1}, {1, 2}}}},
+	{"(0)", "ab", []Match{[]Group{}}},
+	{"(a)b", "ab", []Match{[]Group{{0, 2}, {0, 1}}}},
+	{"a(b)", "ab", []Match{[]Group{{0, 2}, {1, 2}}}},
+	{"(a|b)", "ab", []Match{[]Group{{0, 1}, {0, 1}}, []Group{{1, 2}, {1, 2}}}},
+	{"(a)|(b)", "ab", []Match{[]Group{{0, 1}, {0, 1}, {-1, -1}}, []Group{{1, 2}, {-1, -1}, {1, 2}}}},
+	{"(a+)(a)", "aaaa", []Match{[]Group{{0, 4}, {0, 3}, {3, 4}}}},
+	{"(a+)|(a)", "aaaa", []Match{[]Group{{0, 4}, {0, 4}, {-1, -1}}}},
+	{"(a+)(aa)", "aaaa", []Match{[]Group{{0, 4}, {0, 2}, {2, 4}}}},
+	{"(aaaa)|(aaaa)", "aaaa", []Match{[]Group{{0, 4}, {0, 4}, {-1, -1}}}},
+	{"(aaa)|(aaaa)", "aaaa", []Match{[]Group{{0, 4}, {-1, -1}, {0, 4}}}},
+	{"(aaa)|(aaaa)", "aaaa", []Match{[]Group{{0, 4}, {-1, -1}, {0, 4}}}},
+	{"(aaaa)|(aaa)", "aaaa", []Match{[]Group{{0, 4}, {0, 4}, {-1, -1}}}},
+	{"(a)|(aa)", "aa", []Match{[]Group{{0, 2}, {-1, -1}, {0, 2}}}},
+}
+
 func TestFindAllMatches(t *testing.T) {
 	for _, test := range reTests {
 		t.Run(test.re+"	"+test.str, func(t *testing.T) {
@@ -172,3 +194,22 @@ func TestFindAllMatches(t *testing.T) {
 		})
 	}
 }
+
+func TestFindAllGroups(t *testing.T) {
+	for _, test := range groupTests {
+		t.Run(test.re+"	"+test.str, func(t *testing.T) {
+			re_postfix := shuntingYard(test.re)
+			startState, numGroups := thompson(re_postfix)
+			matchIndices := findAllMatches(startState, []rune(test.str), numGroups)
+			for i := range matchIndices {
+				for j := range matchIndices[i] {
+					if matchIndices[i][j].isValid() {
+						if test.result[i][j] != matchIndices[i][j] {
+							t.Errorf("Wanted %v	Got %v\n", test.result, matchIndices)
+						}
+					}
+				}
+			}
+		})
+	}
+}