cache: factor fs cache into lib/cache

lib/cache/cache_test.go

@@ -0,0 +1,174 @@
+package cache
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+var (
+	called      = 0
+	errSentinel = errors.New("an error")
+	errCached   = errors.New("a cached error")
+)
+
+func setup(t *testing.T) (*Cache, CreateFunc) {
+	called = 0
+	create := func(path string) (interface{}, bool, error) {
+		assert.Equal(t, 0, called)
+		called++
+		switch path {
+		case "/":
+			return "/", true, nil
+		case "/file.txt":
+			return "/file.txt", true, errCached
+		case "/error":
+			return nil, false, errSentinel
+		}
+		panic(fmt.Sprintf("Unknown path %q", path))
+	}
+	c := New()
+	return c, create
+}
+
+func TestGet(t *testing.T) {
+	c, create := setup(t)
+
+	assert.Equal(t, 0, len(c.cache))
+
+	f, err := c.Get("/", create)
+	require.NoError(t, err)
+
+	assert.Equal(t, 1, len(c.cache))
+
+	f2, err := c.Get("/", create)
+	require.NoError(t, err)
+
+	assert.Equal(t, f, f2)
+}
+
+func TestGetFile(t *testing.T) {
+	c, create := setup(t)
+
+	assert.Equal(t, 0, len(c.cache))
+
+	f, err := c.Get("/file.txt", create)
+	require.Equal(t, errCached, err)
+
+	assert.Equal(t, 1, len(c.cache))
+
+	f2, err := c.Get("/file.txt", create)
+	require.Equal(t, errCached, err)
+
+	assert.Equal(t, f, f2)
+}
+
+func TestGetError(t *testing.T) {
+	c, create := setup(t)
+
+	assert.Equal(t, 0, len(c.cache))
+
+	f, err := c.Get("/error", create)
+	require.Equal(t, errSentinel, err)
+	require.Equal(t, nil, f)
+
+	assert.Equal(t, 0, len(c.cache))
+}
+
+func TestPut(t *testing.T) {
+	c, create := setup(t)
+
+	assert.Equal(t, 0, len(c.cache))
+
+	c.Put("/alien", "slime")
+
+	assert.Equal(t, 1, len(c.cache))
+
+	fNew, err := c.Get("/alien", create)
+	require.NoError(t, err)
+	require.Equal(t, "slime", fNew)
+
+	assert.Equal(t, 1, len(c.cache))
+}
+
+func TestCacheExpire(t *testing.T) {
+	c, create := setup(t)
+
+	c.expireInterval = time.Millisecond
+	assert.Equal(t, false, c.expireRunning)
+
+	_, err := c.Get("/", create)
+	require.NoError(t, err)
+
+	c.mu.Lock()
+	entry := c.cache["/"]
+
+	assert.Equal(t, 1, len(c.cache))
+	c.mu.Unlock()
+	c.cacheExpire()
+	c.mu.Lock()
+	assert.Equal(t, 1, len(c.cache))
+	entry.lastUsed = time.Now().Add(-c.expireDuration - 60*time.Second)
+	assert.Equal(t, true, c.expireRunning)
+	c.mu.Unlock()
+	time.Sleep(10 * time.Millisecond)
+	c.mu.Lock()
+	assert.Equal(t, false, c.expireRunning)
+	assert.Equal(t, 0, len(c.cache))
+	c.mu.Unlock()
+}
+
+func TestClear(t *testing.T) {
+	c, create := setup(t)
+
+	assert.Equal(t, 0, len(c.cache))
+
+	_, err := c.Get("/", create)
+	require.NoError(t, err)
+
+	assert.Equal(t, 1, len(c.cache))
+
+	c.Clear()
+
+	assert.Equal(t, 0, len(c.cache))
+}
+
+func TestEntries(t *testing.T) {
+	c, create := setup(t)
+
+	assert.Equal(t, 0, c.Entries())
+
+	_, err := c.Get("/", create)
+	require.NoError(t, err)
+
+	assert.Equal(t, 1, c.Entries())
+
+	c.Clear()
+
+	assert.Equal(t, 0, c.Entries())
+}
+
+func TestGetMaybe(t *testing.T) {
+	c, create := setup(t)
+
+	value, found := c.GetMaybe("/")
+	assert.Equal(t, false, found)
+	assert.Nil(t, value)
+
+	f, err := c.Get("/", create)
+	require.NoError(t, err)
+
+	value, found = c.GetMaybe("/")
+	assert.Equal(t, true, found)
+	assert.Equal(t, f, value)
+
+	c.Clear()
+
+	value, found = c.GetMaybe("/")
+	assert.Equal(t, false, found)
+	assert.Nil(t, value)
+}