Adding upstream version 2.5.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

index/scorch/regexp_test.go

@@ -0,0 +1,57 @@
+//  Copyright (c) 2020 Couchbase, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 		http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package scorch
+
+import (
+	"regexp/syntax"
+	"testing"
+)
+
+func TestLiteralPrefix(t *testing.T) {
+	tests := []struct {
+		input, expected string
+	}{
+		{"", ""},
+		{"hello", "hello"},
+		{"hello.?", "hello"},
+		{"hello$", "hello"},
+		{`[h][e][l][l][o].*world`, "hello"},
+		{`[h-h][e-e][l-l][l-l][o-o].*world`, "hello"},
+		{".*", ""},
+		{"h.*", "h"},
+		{"h.?", "h"},
+		{"h[a-z]", "h"},
+		{`h\s`, "h"},
+		{`(hello)world`, ""},
+		{`日本語`, "日本語"},
+		{`日本語\w`, "日本語"},
+		{`^hello`, ""},
+		{`^`, ""},
+		{`$`, ""},
+		{`(?i)mArTy`, ""},
+	}
+
+	for i, test := range tests {
+		s, err := syntax.Parse(test.input, syntax.Perl)
+		if err != nil {
+			t.Fatalf("expected no syntax.Parse error, got: %v", err)
+		}
+
+		got := literalPrefix(s)
+		if test.expected != got {
+			t.Fatalf("test: %d, %+v, got: %s", i, test, got)
+		}
+	}
+}