nativeaudio

commit 87d71a25c6d58dc8ebef4d3c1d83a5c86a515206
parent a76078f6f04315c96eda344fe139037836a55900
Author: Jack Mordaunt <jackmordaunt.dev@gmail.com>
Date:   Sat, 19 Sep 2026 15:10:27 -0300

test: check the linked backend against the ffmpeg on the same machine

Both sides come from one install and move together, so unlike the
checked-in reference this comparison cannot go stale.

Diffstat:
A
internal/test/linked_test.go
 | 
46
++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 46 insertions(+), 0 deletions(-)
diff --git a/internal/test/linked_test.go b/internal/test/linked_test.go
@@ -0,0 +1,46 @@
+//go:build linux && cgo
+
+package test
+
+import (
+	"bytes"
+	"testing"
+
+	"git.sr.ht/~jackmordaunt/nativeaudio"
+)
+
+// TestLinkedMatchesSubprocess compares the linked backend against the
+// ffmpeg binary installed on the same machine.
+//
+// The reference PCM checked into this directory ages: it was produced by
+// one ffmpeg, and a later one decodes the same file to a different amount
+// of trailing silence. This comparison cannot age, because both sides
+// come from the same install and move together. It is also the only
+// check that would notice the linked backend drifting away from the tool
+// it is meant to be equivalent to, which a frozen reference stops being
+// able to see once the two have diverged for unrelated reasons.
+func TestLinkedMatchesSubprocess(t *testing.T) {
+	for _, name := range []string{"compressed.m4a", "mixkit-game-level-music-689.wav"} {
+		t.Run(name, func(t *testing.T) {
+			reference, rf, err := nativeaudio.FFmpegLoad(name)
+			if err != nil {
+				t.Fatalf("decoding with the ffmpeg binary: %v", err)
+			}
+			linked, lf, err := newDecoder(t).DecodeFile(name)
+			if err != nil {
+				t.Fatalf("decoding with the linked backend: %v", err)
+			}
+			if lf != rf {
+				t.Fatalf("format mismatch: linked %+v, ffmpeg %+v", lf, rf)
+			}
+			// Worth reporting but not worth failing over: the binary is
+			// free to apply defaults the library API does not, so the two
+			// are held to the same tolerance as any other pair of decoders.
+			t.Logf("byte-identical: %v (linked %d bytes, ffmpeg %d bytes)",
+				bytes.Equal(linked, reference), len(linked), len(reference))
+			if !equal(t, linked, reference, lf.Channels*lf.BytesPerSample) {
+				t.Fatalf("the linked backend disagrees with the ffmpeg binary")
+			}
+		})
+	}
+}