IMG-33: adds simple integration tests for image.Load() (#1462)

* Load() integration test

* Added test-images as submodule

integration/load_test.go

@@ -0,0 +1,141 @@
+//go:build integration
+// +build integration
+
+package integration
+
+import (
+	"bytes"
+	"fmt"
+	"image/png"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/corona10/goimagehash"
+	"github.com/imgproxy/imgproxy/v3/imagetype"
+	"github.com/imgproxy/imgproxy/v3/vips"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+const (
+	similarityThreshold = 5 // Distance between images to be considered similar
+)
+
+// testLoadFolder fetches images iterates over images in the specified folder,
+// runs imgproxy on each image, and compares the result with the reference image
+// which is expected to be in the `integration` folder with the same name
+// but with `.png` extension.
+func testLoadFolder(t *testing.T, cs, sourcePath, folder string) {
+	t.Logf("Testing folder: %s", folder)
+
+	walkPath := path.Join(sourcePath, folder)
+
+	// Iterate over the files in the source folder
+	err := filepath.Walk(walkPath, func(path string, info os.FileInfo, err error) error {
+		require.NoError(t, err)
+
+		// Skip directories
+		if info.IsDir() {
+			return nil
+		}
+
+		// get the base name of the file (8-bpp.png)
+		basePath := filepath.Base(path)
+
+		// Replace the extension with .png
+		referencePath := strings.TrimSuffix(basePath, filepath.Ext(basePath)) + ".png"
+
+		// Construct the full path to the reference image (integration/ folder)
+		referencePath = filepath.Join(sourcePath, "integration", folder, referencePath)
+
+		// Construct the source URL for imgproxy (no processing)
+		sourceUrl := fmt.Sprintf("insecure/plain/local:///%s/%s@png", folder, basePath)
+
+		imgproxyImageBytes := fetchImage(t, cs, sourceUrl)
+		imgproxyImage, err := png.Decode(bytes.NewReader(imgproxyImageBytes))
+		require.NoError(t, err, "Failed to decode PNG image from imgproxy for %s", basePath)
+
+		referenceFile, err := os.Open(referencePath)
+		require.NoError(t, err)
+		defer referenceFile.Close()
+
+		referenceImage, err := png.Decode(referenceFile)
+		require.NoError(t, err, "Failed to decode PNG reference image for %s", referencePath)
+
+		hash1, err := goimagehash.DifferenceHash(imgproxyImage)
+		require.NoError(t, err)
+
+		hash2, err := goimagehash.DifferenceHash(referenceImage)
+		require.NoError(t, err)
+
+		distance, err := hash1.Distance(hash2)
+		require.NoError(t, err)
+
+		assert.LessOrEqual(t, distance, similarityThreshold,
+			"Image %s differs from reference image %s by %d, which is greater than the allowed threshold of %d",
+			basePath, referencePath, distance, similarityThreshold)
+
+		return nil
+	})
+
+	require.NoError(t, err)
+}
+
+// TestLoadSaveToPng ensures that our load pipeline works,
+// including standard and custom loaders. For each source image
+// in the folder, it does the passthrough request through imgproxy:
+// no processing, just convert format of the source file to png.
+// Then, it compares the result with the reference image.
+func TestLoadSaveToPng(t *testing.T) {
+	ctx := t.Context()
+
+	// TODO: Will be moved to test suite (like in processing_test.go)
+	// Since we use SupportsLoad, we need to initialize vips
+	defer vips.Shutdown() // either way it needs to be deinitialized
+	err := vips.Init()
+	require.NoError(t, err, "Failed to initialize vips")
+
+	path, err := testImagesPath(t)
+	require.NoError(t, err)
+
+	cs := startImgproxy(t, ctx, path)
+
+	if vips.SupportsLoad(imagetype.GIF) {
+		testLoadFolder(t, cs, path, "gif")
+	}
+
+	if vips.SupportsLoad(imagetype.JPEG) {
+		testLoadFolder(t, cs, path, "jpg")
+	}
+
+	if vips.SupportsLoad(imagetype.HEIC) {
+		testLoadFolder(t, cs, path, "heif")
+	}
+
+	if vips.SupportsLoad(imagetype.JXL) {
+		testLoadFolder(t, cs, path, "jxl")
+	}
+
+	if vips.SupportsLoad(imagetype.SVG) {
+		testLoadFolder(t, cs, path, "svg")
+	}
+
+	if vips.SupportsLoad(imagetype.TIFF) {
+		testLoadFolder(t, cs, path, "tiff")
+	}
+
+	if vips.SupportsLoad(imagetype.WEBP) {
+		testLoadFolder(t, cs, path, "webp")
+	}
+
+	if vips.SupportsLoad(imagetype.BMP) {
+		testLoadFolder(t, cs, path, "bmp")
+	}
+
+	if vips.SupportsLoad(imagetype.ICO) {
+		testLoadFolder(t, cs, path, "ico")
+	}
+}