handle caret properly and add test cases

Author: alexandernorth

pkg/utils/leaf_convert.go

@@ -273,24 +273,32 @@ func ConvertInt64(value string, lst *sdcpb.SchemaLeafType) (*sdcpb.TypedValue, e
 	return convertInt(value, lst.Range, ranges)
 }
 
-func EnsureEscaped(s string, toEscape string) string {
-	isTarget := func(r rune) bool { return strings.ContainsRune(toEscape, r) }
+func XMLRegexConvert(s string) string {
+
+	cTest := func(r rune, prev rune) bool {
+		// if ^ is not following a [ or if $ we want to return true
+		return (r == '^' && prev != '[') || r == '$'
+	}
 
 	b := strings.Builder{}
 	b.Grow(len(s) + len(s)/4)
 	slashes := 0
+	prevR := rune(0)
 
 	for _, r := range s {
 		if r == '\\' {
 			slashes++
+			prevR = r
 			b.WriteRune(r)
 			continue
 		}
 
-		if isTarget(r) && slashes%2 == 0 {
+		if cTest(r, prevR) && slashes%2 == 0 {
 			b.WriteRune('\\')
 		}
+
 		slashes = 0
+		prevR = r
 		b.WriteRune(r)
 	}
 	return b.String()
@@ -317,8 +325,8 @@ func ConvertString(value string, lst *sdcpb.SchemaLeafType) (*sdcpb.TypedValue,
 		// the set of metacharacters defined in go is: \.+*?()|[]{}^$ (go/libexec/src/regexp/regexp.go:714)
 		// we need therefore to escape some values
 		// TODO check about '^'
-	
-		escaped := EnsureEscaped(sp.Pattern, "$")
+
+		escaped := XMLRegexConvert(sp.Pattern)
 		re, err := regexp.Compile(escaped)
 		if err != nil {
 			log.Errorf("unable to compile regex %q", sp.Pattern)

pkg/utils/leaf_convert_test.go

@@ -0,0 +1,63 @@
+package utils
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestXMLRegexConvert(t *testing.T) {
+
+	tests := []struct {
+		name string
+		in   string
+		want string
+	}{
+		{
+			name: "anchors become literals",
+			in:   `^\d+$`,
+			want: `\^\d+\$`,
+		},
+		{
+			name: "already-escaped anchors stay escaped",
+			in:   `foo\$bar`,
+			want: `foo\$bar`,
+		},
+		{
+			name: "caret in char class is left alone, dollar is escaped",
+			in:   `[^\w]+$`,
+			want: `[^\w]+\$`,
+		},
+		{
+			name: "caret later inside char class is escaped",
+			in:   `[a^b]`,
+			want: `[a\^b]`,
+		},
+		{
+			name: "caret escaped inside char class is escaped",
+			in:   `[\^]`,
+			want: `[\^]`,
+		},
+		{
+			name: "caret in char class multiple times, dollar is escaped",
+			in:   `[^a^b]`,
+			want: `[^a\^b]`,
+		},
+		{
+			name: "anchors preceded by a single back-slash stay escaped",
+			in:   `\^test\$`,
+			want: `\^test\$`,
+		},
+		{
+			name: "empty string",
+			in:   ``,
+			want: ``,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := XMLRegexConvert(tt.in); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("XMLRegexConvert() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}