package libimport (	"errors"	"regexp"	"strconv"	"strings"	"testing"	"unicode/utf8"	"golang.org/x/crypto/argon2")var tokenRegex = regexp.MustCompile("^[a-zA-Z0-9]+$")func TestGenerateToken(t *testing.T) {	for i := range 20 {		i++		token := AlphanumericToken(uint(i))		if utf8.RuneCountInString(token) != i {			t.Errorf(`GenerateToken("%v") FAILED. Mismatched lengths.`, i)		}		if !tokenRegex.Match([]byte(token)) {			t.Errorf(`GenerateToken("%v") FAILED. Not alphanumerical. Returned: %s`, i, token)		}	}}func TestGenerateSalt(t *testing.T) {	salt, err := GenerateSalt(16)	if err != nil {		t.Fatalf("GenerateSalt(16): %v", err)	}	if len(salt) != 16 {		t.Errorf("GenerateSalt(16) returned %d bytes, want 16", len(salt))	}	salt2, err := GenerateSalt(16)	if err != nil {		t.Fatalf("GenerateSalt(16) #2: %v", err)	}	if string(salt) == string(salt2) {		t.Error("GenerateSalt returned the same salt twice")	}}func TestGenerateHashValidateHash(t *testing.T) {	hash, err := GenerateHash("hunter2")	if err != nil {		t.Fatalf("GenerateHash: %v", err)	}	if !strings.HasPrefix(hash, "$argon2id$v=") {		t.Errorf("hash %q does not start with $argon2id$v=", hash)	}	match, err := ValidateHash("hunter2", hash)	if err != nil {		t.Fatalf("ValidateHash(correct): %v", err)	}	if !match {		t.Error("ValidateHash(correct password) = false, want true")	}	match, err = ValidateHash("wrong", hash)	if err != nil {		t.Fatalf("ValidateHash(wrong): %v", err)	}	if match {		t.Error("ValidateHash(wrong password) = true, want false")	}}func TestDecodeHash(t *testing.T) {	if _, _, _, err := DecodeHash("not a hash"); !errors.Is(err, ErrInvalidHash) {		t.Errorf("DecodeHash(garbage) = %v, want ErrInvalidHash", err)	}	// a valid-looking hash but for an argon2 version we don't know	wrongVersion := "$argon2id$v=99$m=65536,t=4,p=4$c2FsdHNhbHRzYWx0c2FsdA$c2FsdHNhbHRzYWx0c2FsdHNhbHRzYWx0c2FsdA"	if _, _, _, err := DecodeHash(wrongVersion); !errors.Is(err, ErrIncompatibleVersion) {		t.Errorf("DecodeHash(wrong version) = %v, want ErrIncompatibleVersion", err)	}	// a valid version but undecodable base64 salt	badBase64 := "$argon2id$v=" + strconv.Itoa(argon2.Version) + "$m=65536,t=4,p=4$@@@$c2FsdA"	if _, _, _, err := DecodeHash(badBase64); err == nil {		t.Error("DecodeHash(bad base64) = nil error, want error")	}	// roundtrip through DecodeHash	hash, err := GenerateHash("pw")	if err != nil {		t.Fatalf("GenerateHash: %v", err)	}	p, salt, decoded, err := DecodeHash(hash)	if err != nil {		t.Fatalf("DecodeHash(own hash): %v", err)	}	if len(salt) == 0 || len(decoded) == 0 {		t.Error("DecodeHash returned empty salt or hash")	}	if p.hash_len != uint32(len(decoded)) {		t.Errorf("p.hash_len = %d, want %d", p.hash_len, len(decoded))	}}