Fix primitive.Regex Equal method (#318)

Author: mengskysama

bson/primitive/primitive.go

@@ -70,7 +70,7 @@ func (rp Regex) String() string {
 
 // Equal compares rp to rp2 and returns true is the are equal.
 func (rp Regex) Equal(rp2 Regex) bool {
-	return rp.Pattern == rp2.Pattern && rp.Options == rp.Options
+	return rp.Pattern == rp2.Pattern && rp.Options == rp2.Options
 }
 
 // IsZero returns if rp is the empty Regex

bson/primitive/primitive_test.go

@@ -58,3 +58,23 @@ func TestPrimitiveIsZero(t *testing.T) {
 		})
 	}
 }
+
+func TestRegexCompare(t *testing.T) {
+	testcases := []struct {
+		name string
+		r1   Regex
+		r2   Regex
+		eq   bool
+	}{
+		{"equal", Regex{Pattern: "foo1", Options: "bar1"}, Regex{Pattern: "foo1", Options: "bar1"}, true},
+		{"not equal", Regex{Pattern: "foo1", Options: "bar1"}, Regex{Pattern: "foo2", Options: "bar2"}, false},
+		{"not equal", Regex{Pattern: "foo1", Options: "bar1"}, Regex{Pattern: "foo1", Options: "bar2"}, false},
+		{"not equal", Regex{Pattern: "foo1", Options: "bar1"}, Regex{Pattern: "foo2", Options: "bar1"}, false},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			require.True(t, tc.r1.Equal(tc.r2) == tc.eq)
+		})
+	}
+}