1 files changed, 152 insertions, 0 deletions
diff --git a/internal/http/compression_test.go b/internal/http/compression_test.go
new file mode 100644
index 0000000..b675341
--- /dev/null
+++ b/internal/http/compression_test.go
@@ -0,0 +1,152 @@
+package http
+
+import (
+	"bytes"
+	"compress/flate"
+	"compress/gzip"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/andybalholm/brotli"
+	"github.com/klauspost/compress/zstd"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// ── Decompress ────────────────────────────────────────────────────────────────
+
+func TestDecompress_NoEncoding(t *testing.T) {
+	body := []byte("plain")
+	assert.Equal(t, body, Decompress(http.Header{}, body))
+}
+
+func TestDecompress_UnknownEncoding(t *testing.T) {
+	body := []byte("mystery")
+	assert.Equal(t, body, Decompress(http.Header{"Content-Encoding": []string{"identity"}}, body))
+}
+
+func TestDecompress_Gzip(t *testing.T) {
+	var buf bytes.Buffer
+	w := gzip.NewWriter(&buf)
+	_, err := w.Write([]byte("gzip content"))
+	require.NoError(t, err)
+	w.Close()
+	assert.Equal(t, "gzip content", string(Decompress(http.Header{"Content-Encoding": []string{"gzip"}}, buf.Bytes())))
+}
+
+func TestDecompress_Gzip_Corrupt(t *testing.T) {
+	body := []byte("not gzip")
+	assert.Equal(t, body, Decompress(http.Header{"Content-Encoding": []string{"gzip"}}, body))
+}
+
+func TestDecompress_Deflate(t *testing.T) {
+	var buf bytes.Buffer
+	w, err := flate.NewWriter(&buf, flate.DefaultCompression)
+	require.NoError(t, err)
+	w.Write([]byte("deflate content"))
+	w.Close()
+	assert.Equal(t, "deflate content", string(Decompress(http.Header{"Content-Encoding": []string{"deflate"}}, buf.Bytes())))
+}
+
+func TestDecompress_Deflate_Corrupt(t *testing.T) {
+	body := []byte("not deflate")
+	assert.Equal(t, body, Decompress(http.Header{"Content-Encoding": []string{"deflate"}}, body))
+}
+
+func TestDecompress_Brotli(t *testing.T) {
+	var buf bytes.Buffer
+	w := brotli.NewWriter(&buf)
+	w.Write([]byte("brotli content"))
+	w.Close()
+	assert.Equal(t, "brotli content", string(Decompress(http.Header{"Content-Encoding": []string{"br"}}, buf.Bytes())))
+}
+
+func TestDecompress_Brotli_Corrupt(t *testing.T) {
+	body := []byte("not brotli")
+	assert.Equal(t, body, Decompress(http.Header{"Content-Encoding": []string{"br"}}, body))
+}
+
+func TestDecompress_Zstd(t *testing.T) {
+	enc, err := zstd.NewWriter(nil)
+	require.NoError(t, err)
+	compressed := enc.EncodeAll([]byte("zstd content"), nil)
+	assert.Equal(t, "zstd content", string(Decompress(http.Header{"Content-Encoding": []string{"zstd"}}, compressed)))
+}
+
+func TestDecompress_Zstd_Corrupt(t *testing.T) {
+	body := []byte("not zstd")
+	assert.Equal(t, body, Decompress(http.Header{"Content-Encoding": []string{"zstd"}}, body))
+}
+
+func TestDecompress_CaseInsensitive(t *testing.T) {
+	var buf bytes.Buffer
+	w := gzip.NewWriter(&buf)
+	w.Write([]byte("case"))
+	w.Close()
+	assert.Equal(t, "case", string(Decompress(http.Header{"Content-Encoding": []string{"GZIP"}}, buf.Bytes())))
+}
+
+func TestDecompress_EmptyBody(t *testing.T) {
+	assert.Equal(t, []byte{}, Decompress(http.Header{"Content-Encoding": []string{"gzip"}}, []byte{}))
+}
+
+func TestDecompress_LargeBody(t *testing.T) {
+	large := []byte(strings.Repeat("a", 100000))
+	var buf bytes.Buffer
+	w := gzip.NewWriter(&buf)
+	w.Write(large)
+	w.Close()
+	out := Decompress(http.Header{"Content-Encoding": []string{"gzip"}}, buf.Bytes())
+	assert.Equal(t, large, out)
+}
+
+// ── IsBinary ──────────────────────────────────────────────────────────────────
+
+func TestIsBinary_KnownEncodingsNotBinary(t *testing.T) {
+	// Known encodings we can decompress fall through to the Content-Type check.
+	// image/png is still binary even with a known encoding — the encoding tells
+	// us we can decompress it, but the content type determines binary/text.
+	for _, enc := range []string{"gzip", "deflate", "br", "zstd"} {
+		h := http.Header{
+			"Content-Encoding": []string{enc},
+			"Content-Type":     []string{"text/plain"},
+		}
+		assert.False(t, IsBinary(h), "encoding %s with text/plain should not be binary", enc)
+	}
+	// image/png with a known encoding is still binary.
+	for _, enc := range []string{"gzip", "deflate", "br", "zstd"} {
+		h := http.Header{
+			"Content-Encoding": []string{enc},
+			"Content-Type":     []string{"image/png"},
+		}
+		assert.True(t, IsBinary(h), "encoding %s with image/png should be binary", enc)
+	}
+}
+
+func TestIsBinary_BinaryContentTypes(t *testing.T) {
+	for _, ct := range []string{"image/png", "image/jpeg", "application/octet-stream", "video/mp4", "audio/mpeg"} {
+		h := http.Header{"Content-Type": []string{ct}}
+		assert.True(t, IsBinary(h), "%s should be binary", ct)
+	}
+}
+
+func TestIsBinary_TextContentTypes(t *testing.T) {
+	for _, ct := range []string{
+		"text/plain", "text/html", "text/css",
+		"application/json", "application/xml",
+		"application/javascript", "application/x-www-form-urlencoded",
+		"application/xhtml+xml", "application/ld+json",
+	} {
+		h := http.Header{"Content-Type": []string{ct}}
+		assert.False(t, IsBinary(h), "%s should not be binary", ct)
+	}
+}
+
+func TestIsBinary_EmptyContentType(t *testing.T) {
+	assert.False(t, IsBinary(http.Header{"Content-Type": []string{""}}))
+}
+
+func TestIsBinary_NoHeaders(t *testing.T) {
+	assert.False(t, IsBinary(http.Header{}))
+}