Assert the avatar endpoints serve images rather than byte counts

auth_test.go

@@ -1,8 +1,12 @@
 package auth
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
+	"image"
+	_ "image/jpeg"
+	_ "image/png"
 	"io"
 	"net"
 	"net/http"
@@ -333,7 +337,18 @@ func TestIntegrationAvatar(t *testing.T) {
 
 	b, err := io.ReadAll(resp.Body)
 	require.NoError(t, err)
-	assert.Equal(t, 569, len(b))
+
+	// what the endpoint promises is a decodable image within the resize limit, not a byte count.
+	// the encoders are the standard library's, so their output moves with the Go release: this
+	// assertion read 569 bytes until Go 1.27 changed the compressor and produced 507 for the same
+	// picture, failing a test that nothing had touched
+	img, format, err := image.Decode(bytes.NewReader(b))
+	require.NoError(t, err, "the avatar endpoint has to serve a decodable image")
+	assert.Equal(t, "png", format)
+	bounds := img.Bounds()
+	assert.LessOrEqual(t, bounds.Dx(), 120, "wider than the resize limit")
+	assert.LessOrEqual(t, bounds.Dy(), 120, "taller than the resize limit")
+	assert.NotEmpty(t, b)
 }
 
 func TestIntegrationList(t *testing.T) {

avatar/avatar_test.go

@@ -188,7 +188,11 @@ func TestAvatar_PutIdenticon(t *testing.T) {
 	assert.Equal(t, "http://localhost:8080/avatar/b3daa77b4c04a9551b8781d03191fe098f325e67.image", res)
 	fi, err := os.Stat("/tmp/avatars.test/30/b3daa77b4c04a9551b8781d03191fe098f325e67.image")
 	assert.NoError(t, err)
-	assert.Equal(t, int64(999), fi.Size())
+	// the identicon is encoded by the standard library, so its byte count moves with the Go
+	// release: this read 999 until Go 1.27 changed the encoder. Assert it was written and is a
+	// decodable image instead
+	assert.Positive(t, fi.Size())
+	assertDecodableImage(t, "/tmp/avatars.test/30/b3daa77b4c04a9551b8781d03191fe098f325e67.image")
 
 }
 
@@ -210,9 +214,14 @@ func TestAvatar_PutFailed(t *testing.T) {
 	res, err := p.Put(u, client)
 	require.NoError(t, err)
 	assert.Equal(t, "http://localhost:8080/avatar/a1881c06eec96db9901c7bbfe41c42a3f08e9cb4.image", res)
-	fi, err := os.Stat("/tmp/avatars.test/84/a1881c06eec96db9901c7bbfe41c42a3f08e9cb4.image")
+	avatarPath := "/tmp/avatars.test/84/a1881c06eec96db9901c7bbfe41c42a3f08e9cb4.image"
+	fi, err := os.Stat(avatarPath)
 	require.NoError(t, err)
-	assert.Equal(t, int64(992), fi.Size())
+	// the identicon is encoded by the standard library, so its byte count moves with the Go
+	// release: this read 992 until Go 1.27 changed the encoder. Assert it was written and is a
+	// decodable image instead
+	assert.Positive(t, fi.Size())
+	assertDecodableImage(t, avatarPath)
 }
 
 func TestAvatar_PutCapsBodySize(t *testing.T) {
@@ -602,3 +611,14 @@ func TestAvatar_Retry(t *testing.T) {
 	assert.Error(t, err)
 	assert.True(t, time.Since(st) >= time.Microsecond*5)
 }
+
+// assertDecodableImage checks the file holds an image the standard library can read back, which is
+// what an avatar store owes its caller. Byte counts belong to whichever encoder the Go release ships.
+func assertDecodableImage(t *testing.T, path string) {
+	t.Helper()
+	f, err := os.Open(path) //nolint:gosec // test-controlled path
+	require.NoError(t, err)
+	defer f.Close() //nolint:errcheck // read-only handle in a test
+	_, _, err = image.Decode(f)
+	require.NoError(t, err, "%s has to be a decodable image", path)
+}

v2/auth_test.go

@@ -1,8 +1,12 @@
 package auth
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
+	"image"
+	_ "image/jpeg"
+	_ "image/png"
 	"io"
 	"net"
 	"net/http"
@@ -332,7 +336,18 @@ func TestIntegrationAvatar(t *testing.T) {
 
 	b, err := io.ReadAll(resp.Body)
 	require.NoError(t, err)
-	assert.Equal(t, 569, len(b))
+
+	// what the endpoint promises is a decodable image within the resize limit, not a byte count.
+	// the encoders are the standard library's, so their output moves with the Go release: this
+	// assertion read 569 bytes until Go 1.27 changed the compressor and produced 507 for the same
+	// picture, failing a test that nothing had touched
+	img, format, err := image.Decode(bytes.NewReader(b))
+	require.NoError(t, err, "the avatar endpoint has to serve a decodable image")
+	assert.Equal(t, "png", format)
+	bounds := img.Bounds()
+	assert.LessOrEqual(t, bounds.Dx(), 120, "wider than the resize limit")
+	assert.LessOrEqual(t, bounds.Dy(), 120, "taller than the resize limit")
+	assert.NotEmpty(t, b)
 }
 
 func TestIntegrationList(t *testing.T) {

v2/avatar/avatar_test.go

@@ -188,7 +188,11 @@ func TestAvatar_PutIdenticon(t *testing.T) {
 	assert.Equal(t, "http://localhost:8080/avatar/b3daa77b4c04a9551b8781d03191fe098f325e67.image", res)
 	fi, err := os.Stat("/tmp/avatars.test/30/b3daa77b4c04a9551b8781d03191fe098f325e67.image")
 	assert.NoError(t, err)
-	assert.Equal(t, int64(999), fi.Size())
+	// the identicon is encoded by the standard library, so its byte count moves with the Go
+	// release: this read 999 until Go 1.27 changed the encoder. Assert it was written and is a
+	// decodable image instead
+	assert.Positive(t, fi.Size())
+	assertDecodableImage(t, "/tmp/avatars.test/30/b3daa77b4c04a9551b8781d03191fe098f325e67.image")
 
 }
 
@@ -210,9 +214,14 @@ func TestAvatar_PutFailed(t *testing.T) {
 	res, err := p.Put(u, client)
 	require.NoError(t, err)
 	assert.Equal(t, "http://localhost:8080/avatar/a1881c06eec96db9901c7bbfe41c42a3f08e9cb4.image", res)
-	fi, err := os.Stat("/tmp/avatars.test/84/a1881c06eec96db9901c7bbfe41c42a3f08e9cb4.image")
+	avatarPath := "/tmp/avatars.test/84/a1881c06eec96db9901c7bbfe41c42a3f08e9cb4.image"
+	fi, err := os.Stat(avatarPath)
 	require.NoError(t, err)
-	assert.Equal(t, int64(992), fi.Size())
+	// the identicon is encoded by the standard library, so its byte count moves with the Go
+	// release: this read 992 until Go 1.27 changed the encoder. Assert it was written and is a
+	// decodable image instead
+	assert.Positive(t, fi.Size())
+	assertDecodableImage(t, avatarPath)
 }
 
 func TestAvatar_PutCapsBodySize(t *testing.T) {
@@ -602,3 +611,14 @@ func TestAvatar_Retry(t *testing.T) {
 	assert.Error(t, err)
 	assert.True(t, time.Since(st) >= time.Microsecond*5)
 }
+
+// assertDecodableImage checks the file holds an image the standard library can read back, which is
+// what an avatar store owes its caller. Byte counts belong to whichever encoder the Go release ships.
+func assertDecodableImage(t *testing.T, path string) {
+	t.Helper()
+	f, err := os.Open(path) //nolint:gosec // test-controlled path
+	require.NoError(t, err)
+	defer f.Close() //nolint:errcheck // read-only handle in a test
+	_, _, err = image.Decode(f)
+	require.NoError(t, err, "%s has to be a decodable image", path)
+}