hst/instance: define instance state

This is now part of the hst API. This change also improves identifier generation and serialisation.

Signed-off-by: Ophestra <cat@gensokyo.uk>

hst/instance_test.go

@@ -0,0 +1,113 @@
+package hst_test
+
+import (
+	"encoding/hex"
+	"errors"
+	"reflect"
+	"testing"
+	"time"
+	_ "unsafe"
+
+	"hakurei.app/hst"
+)
+
+//go:linkname newInstanceID hakurei.app/hst.newInstanceID
+func newInstanceID(id *hst.ID, p uint64) error
+
+func TestIdentifierDecodeError(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name string
+		err  error
+		want string
+	}{
+		{"invalid byte", hst.IdentifierDecodeError{Err: hex.InvalidByteError(0)},
+			"got invalid byte U+0000 in identifier"},
+		{"odd length", hst.IdentifierDecodeError{Err: hex.ErrLength},
+			"odd length identifier hex string"},
+		{"passthrough", hst.IdentifierDecodeError{Err: hst.ErrIdentifierLength},
+			hst.ErrIdentifierLength.Error()},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			if got := tc.err.Error(); got != tc.want {
+				t.Errorf("Error: %q, want %q", got, tc.want)
+			}
+		})
+	}
+
+	t.Run("unwrap", func(t *testing.T) {
+		t.Parallel()
+
+		err := hst.IdentifierDecodeError{Err: hst.ErrIdentifierLength}
+		if !errors.Is(err, hst.ErrIdentifierLength) {
+			t.Errorf("Is unexpected false")
+		}
+	})
+}
+
+func TestID(t *testing.T) {
+	t.Parallel()
+
+	var randomID hst.ID
+	if err := hst.NewInstanceID(&randomID); err != nil {
+		t.Fatalf("NewInstanceID: error = %v", err)
+	}
+
+	testCases := []struct {
+		name string
+		data string
+		want hst.ID
+		err  error
+	}{
+		{"bad length", "meow", hst.ID{},
+			hst.IdentifierDecodeError{Err: hst.ErrIdentifierLength}},
+		{"invalid byte", "02bc7f8936b2af6\x00\x00e2535cd71ef0bb7", hst.ID{},
+			hst.IdentifierDecodeError{Err: hex.InvalidByteError(0)}},
+
+		{"zero", "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", hst.ID{}, nil},
+		{"random", randomID.String(), randomID, nil},
+		{"sample", "ba21c9bd33d9d37917288281a2a0d239", hst.ID{
+			0xba, 0x21, 0xc9, 0xbd,
+			0x33, 0xd9, 0xd3, 0x79,
+			0x17, 0x28, 0x82, 0x81,
+			0xa2, 0xa0, 0xd2, 0x39}, nil},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			var got hst.ID
+			if err := got.UnmarshalText([]byte(tc.data)); !reflect.DeepEqual(err, tc.err) {
+				t.Errorf("UnmarshalText: error = %#v, want %#v", err, tc.err)
+			}
+
+			if tc.err == nil {
+				if gotString := got.String(); gotString != tc.data {
+					t.Errorf("String: %q, want %q", gotString, tc.data)
+				}
+				if gotData, _ := got.MarshalText(); string(gotData) != tc.data {
+					t.Errorf("MarshalText: %q, want %q", string(gotData), tc.data)
+				}
+			}
+		})
+	}
+
+	t.Run("time", func(t *testing.T) {
+		t.Parallel()
+		var id hst.ID
+
+		now := time.Now()
+		if err := newInstanceID(&id, uint64(now.UnixNano())); err != nil {
+			t.Fatalf("newInstanceID: error = %v", err)
+		}
+
+		got := id.CreationTime()
+		if !got.Equal(now) {
+			t.Fatalf("CreationTime(%q): %s, want %s", id.String(), got, now)
+		}
+	})
+}