add tests around MatchNamedCaptureGroups + rename

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

internal/regex_helpers_test.go

@@ -0,0 +1,70 @@
+package internal
+
+import (
+	"regexp"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMatchCaptureGroups(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		pattern  string
+		expected map[string]string
+	}{
+		{
+			name:    "go-case",
+			input:   "match this thing",
+			pattern: `(?P<name>match).*(?P<version>thing)`,
+			expected: map[string]string{
+				"name":    "match",
+				"version": "thing",
+			},
+		},
+		{
+			name:    "only matches the first instance",
+			input:   "match this thing batch another think",
+			pattern: `(?P<name>[mb]atch).*?(?P<version>thin[gk])`,
+			expected: map[string]string{
+				"name":    "match",
+				"version": "thing",
+			},
+		},
+		{
+			name:    "nested capture groups",
+			input:   "cool something to match against",
+			pattern: `((?P<name>match) (?P<version>against))`,
+			expected: map[string]string{
+				"name":    "match",
+				"version": "against",
+			},
+		},
+		{
+			name:    "nested optional capture groups",
+			input:   "cool something to match against",
+			pattern: `((?P<name>match) (?P<version>against))?`,
+			expected: map[string]string{
+				"name":    "match",
+				"version": "against",
+			},
+		},
+		{
+			name:    "nested optional capture groups with larger match",
+			input:   "cool something to match against match never",
+			pattern: `.*?((?P<name>match) (?P<version>(against|never)))?`,
+			expected: map[string]string{
+				"name":    "match",
+				"version": "against",
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			actual := MatchNamedCaptureGroups(regexp.MustCompile(test.pattern), test.input)
+			assert.Equal(t, test.expected, actual)
+		})
+	}
+}