Unit test for image ref glob matching, with support for **

glob_test.go

package glob_test

import (
	"fmt"
	"regexp"
	"strings"
	"testing"

	"github.com/google/go-containerregistry/pkg/name"
)

func TestGlob(t *testing.T) {
	t.Parallel()
	for _, c := range cases {
		t.Run(c.in+"|"+c.glob, func(t *testing.T) {
			match, err := glob(c.in, c.glob)
			if match != c.wantMatch {
				t.Errorf("match: got %t, want %t", match, c.wantMatch)
			}
			if gotErr := err != nil; gotErr != c.wantErr {
				t.Errorf("err: got %v, want %t", err, c.wantErr)
			}
		})
	}
}

var validGlob = regexp.MustCompile(`^[a-zA-Z0-9-_:\/\*\.]+$`)

func glob(in, glob string) (bool, error) {
	ref, err := name.ParseReference(in, name.WeakValidation)
	if err != nil {
		return false, err
	}

	// Reject that glob doesn't look like a regexp
	if !validGlob.MatchString(glob) {
		return false, fmt.Errorf("invalid glob %q", glob)
	}

	// Translate glob to regexp.
	glob = strings.ReplaceAll(glob, ".", `\.`)    // . in glob means \. in regexp
	glob = strings.ReplaceAll(glob, "**", ".+")   // ** in glob means .+ in regexp
	glob = strings.ReplaceAll(glob, "*", "[^/]+") // * in glob means any non-/ in regexp
	glob = fmt.Sprintf("^%s$", glob)              // glob must match the whole string

	// TODO: do we want : to count as a separator like / is?

	return regexp.MatchString(glob, ref.Name())
}

var cases = []struct {
	in, glob           string
	wantMatch, wantErr bool
}{
	{"ubuntu", "index.docker.io/library/ubuntu:latest", true, false},
	{"ubuntu", "index.docker.io/library/ubuntu:*", true, false},
	{"ubuntu", "index.docker.io/library/*", true, false},
	{"ubuntu", "index.docker.io/library/*:latest", true, false},
	{"ubuntu", "index.docker.io/*/*", true, false},
	{"ubuntu", "index.docker.io/**", true, false},
	{"ubuntu", "index.docker.**", true, false},
	{"ubuntu", "inde**", true, false},
	{"ubuntu", "**", true, false},
	{"myuser/myapp", "index.docker.io/myuser/myapp:latest", true, false},
	{"myuser/myapp", "index.docker.io/myuser/myapp:*", true, false},
	{"myuser/myapp", "index.docker.io/myuser/*", true, false},
	{"myuser/myapp", "index.docker.io/myuser/*:latest", true, false},
	{"myuser/myapp", "index.docker.io/*/*", true, false},
	{"myuser/myapp", "index.docker.io/**", true, false},
	{"myuser/myapp", "index.docker.**", true, false},
	{"myuser/myapp", "inde**", true, false},
	{"myuser/myapp", "**", true, false},
	{"ghcr.io/foo/bar", "ghcr.io/*/*", true, false},
	{"ghcr.io/foo/bar", "ghcr.io/**", true, false},
	{"ghcr.io/foo", "ghcr.io/*/*", false, false},
	{"ghcr.io/foo", "ghcr.io/**", true, false},
	{"ghcr.io/foo", "ghc**", true, false},
	{"ghcr.io/foo", "**", true, false},
	{"prefix-ghcr.io/foo", "ghcr.io/foo", false, false}, // glob starts at beginning.
	{"ghcr.io/foo-suffix", "ghcr.io/foo", false, false}, // glob ends at the end.
	{"ghcrxio/foo", "ghcr.io/**", false, false},         // dots in glob are replaced with \., not treated as regexp .
	{"invalid&name", "**", false, true},                 // invalid refs are not matched.
	{"invalid-glob", ".+", false, true},                 // invalid globs are rejected.
	{"invalid-glob", "[a-z]*", false, true},             // invalid globs are rejected.
}