Add tests for regex character classes (#4155)

Signed-off-by: George Robinson <[email protected]>

matcher/parse/lexer_test.go

@@ -372,6 +372,32 @@ func TestLexer_Scan(t *testing.T) {
 				columnEnd:   13,
 			},
 		}},
+	}, {
+		name:  "quoted with regex digit character class",
+		input: "\"\\d+\"",
+		expected: []token{{
+			kind:  tokenQuoted,
+			value: "\"\\d+\"",
+			position: position{
+				offsetStart: 0,
+				offsetEnd:   5,
+				columnStart: 0,
+				columnEnd:   5,
+			},
+		}},
+	}, {
+		name:  "quoted with escaped regex digit character class",
+		input: "\"\\\\d+\"",
+		expected: []token{{
+			kind:  tokenQuoted,
+			value: "\"\\\\d+\"",
+			position: position{
+				offsetStart: 0,
+				offsetEnd:   6,
+				columnStart: 0,
+				columnEnd:   6,
+			},
+		}},
 	}, {
 		name:  "quoted with escaped quotes",
 		input: "\"hello \\\"world\\\"\"",

matcher/parse/parse_test.go

@@ -99,6 +99,10 @@ func TestMatchers(t *testing.T) {
 		name:     "match regex in quotes",
 		input:    "{\"foo\"=~\"[a-z]+\"}",
 		expected: labels.Matchers{mustNewMatcher(t, labels.MatchRegexp, "foo", "[a-z]+")},
+	}, {
+		name:     "match regex digit in quotes",
+		input:    "{\"foo\"=~\"\\\\d+\"}",
+		expected: labels.Matchers{mustNewMatcher(t, labels.MatchRegexp, "foo", "\\d+")},
 	}, {
 		name:     "doesn't match regex in quotes",
 		input:    "{\"foo\"!~\"[a-z]+\"}",
@@ -203,6 +207,10 @@ func TestMatchers(t *testing.T) {
 		name:  "invalid escape sequence",
 		input: "{foo=\"bar\\w\"}",
 		error: "5:12: \"bar\\w\": invalid input",
+	}, {
+		name:  "invalid escape sequence regex digits",
+		input: "{\"foo\"=~\"\\d+\"}",
+		error: "8:13: \"\\d+\": invalid input",
 	}, {
 		name:  "no unquoted escape sequences",
 		input: "{foo=bar\\n}",