add more image tests, generalize prep for those tests

backend/app/store/image/image.go

@@ -1,4 +1,5 @@
-// Package image handles storing, resizing and retrival of images
+// Package image handles storing, resizing and retrieval of images
+// Provides Interface with Save and Load and one implementation on top of local file system.
 package image
 
 import (
@@ -25,9 +26,9 @@ type Interface interface {
 
 // FileSystem provides image Interface for local files. Saves and loads files from Location, restricts max size
 type FileSystem struct {
-	Location  string
-	MaxSize   int
-	Partitons int
+	Location   string
+	MaxSize    int
+	Partitions int
 
 	crc struct {
 		*crc64.Table
@@ -98,13 +99,13 @@ func (f *FileSystem) Load(id string) (io.ReadCloser, int64, error) {
 // in different subdirectories and avoid too many files in a single place.
 // the end result is a full path like this - /tmp/images/92. Number of partitions defined by FileSystem.Partitions
 func (f *FileSystem) location(id string) string {
-	if f.Partitons == 0 {
+	if f.Partitions == 0 {
 		return f.Location
 	}
 
 	f.crc.Do(func() {
 		f.crc.Table = crc64.MakeTable(crc64.ECMA)
-		p := int(math.Round(math.Log10(float64(f.Partitons))))
+		p := int(math.Round(math.Log10(float64(f.Partitions))))
 		f.crc.mask = "%0" + strconv.Itoa(p) + "d"
 		f.crc.divider = uint64(math.Pow(10, float64(p)))
 	})

backend/app/store/image/image_test.go

@@ -2,6 +2,7 @@ package image
 
 import (
 	"io/ioutil"
+	"math/rand"
 	"os"
 	"path"
 	"strconv"
@@ -13,57 +14,39 @@ import (
 )
 
 func TestImage_Save(t *testing.T) {
-	loc, err := ioutil.TempDir("", "test_image_r42")
-	require.NoError(t, err, "failed to make temp dir")
-	defer os.RemoveAll(loc)
+	svc, teardown := prepareImageTest(t)
+	defer teardown()
 
-	svc := FileSystem{
-		Location:  loc,
-		Partitons: 100,
-		MaxSize:   50,
-	}
 	id, err := svc.Save("blah_ff1.png", strings.NewReader("blah blah"))
 	assert.NoError(t, err)
 	assert.Equal(t, "fc77a87ad3c898b9603119711f99305145e272e103c904d85ee2deda.png", id)
 
-	dst := path.Join(loc, "56", id)
+	dst := path.Join(svc.Location, "56", id)
 	data, err := ioutil.ReadFile(dst)
 	assert.NoError(t, err)
 	assert.Equal(t, "blah blah", string(data))
 }
 
 func TestImage_SaveTooLarge(t *testing.T) {
-	loc, err := ioutil.TempDir("", "test_image_r42")
-	require.NoError(t, err, "failed to make temp dir")
-	defer os.RemoveAll(loc)
-
-	svc := FileSystem{
-		Location:  loc,
-		Partitons: 100,
-		MaxSize:   5,
-	}
-	_, err = svc.Save("blah_ff1.png", strings.NewReader("blah blah"))
+	svc, teardown := prepareImageTest(t)
+	defer teardown()
+	svc.MaxSize = 5
+	_, err := svc.Save("blah_ff1.png", strings.NewReader("blah blah"))
 	assert.Error(t, err)
 	assert.EqualError(t, err, "file blah_ff1.png is too large")
 }
 
 func TestImage_Load(t *testing.T) {
-	loc, err := ioutil.TempDir("", "test_image_r42")
-	require.NoError(t, err, "failed to make temp dir")
-	defer os.RemoveAll(loc)
 
-	// save image
-	svc := FileSystem{
-		Location:  loc,
-		Partitons: 100,
-		MaxSize:   50,
-	}
+	svc, teardown := prepareImageTest(t)
+	defer teardown()
+
 	id, err := svc.Save("blah_ff1.png", strings.NewReader("blah blah"))
 	assert.NoError(t, err)
 
 	r, sz, err := svc.Load(id)
 	assert.NoError(t, err)
-	defer r.Close()
+	defer func() { assert.NoError(t, r.Close()) }()
 	data, err := ioutil.ReadAll(r)
 	assert.NoError(t, err)
 	assert.Equal(t, "blah blah", string(data))
@@ -83,12 +66,52 @@ func TestImage_location(t *testing.T) {
 		{100, "12345", "/tmp/69"},
 		{100, "xyzz", "/tmp/58"},
 		{100, "6851dcde6024e03258a66705f29e14b506048c74.png", "/tmp/02"},
+		{5, "6851dcde6024e03258a66705f29e14b506048c74.png", "/tmp/2"},
+		{5, "xxxyz.png", "/tmp/0"},
 		{0, "12345", "/tmp"},
 	}
 	for n, tt := range tbl {
 		t.Run(strconv.Itoa(n), func(t *testing.T) {
-			svc := FileSystem{Location: "/tmp", Partitons: tt.partitions}
+			svc := FileSystem{Location: "/tmp", Partitions: tt.partitions}
 			assert.Equal(t, tt.res, svc.location(tt.id))
 		})
 	}
+
+	// generate random names and make sure partition never runs out of allowed
+	letterRunes := []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+	randomString := func(n int) string {
+		b := make([]rune, n)
+		for i := range b {
+			b[i] = letterRunes[rand.Intn(len(letterRunes))]
+		}
+		return string(b)
+	}
+
+	svc := FileSystem{Location: "/tmp", Partitions: 10}
+	for i := 0; i < 1000; i++ {
+		v := randomString(rand.Intn(64))
+		parts := strings.Split(svc.location(v), "/")
+		p, err := strconv.Atoi(parts[len(parts)-1])
+		require.NoError(t, err)
+		assert.True(t, p >= 0 && p < 10)
+	}
+}
+
+func prepareImageTest(t *testing.T) (svc FileSystem, teardown func()) {
+	loc, err := ioutil.TempDir("", "test_image_r42")
+	require.NoError(t, err, "failed to make temp dir")
+
+	svc = FileSystem{
+		Location:   loc,
+		Partitions: 100,
+		MaxSize:    50,
+	}
+
+	teardown = func() {
+		defer func() {
+			assert.NoError(t, os.RemoveAll(loc))
+		}()
+	}
+
+	return svc, teardown
 }