feat: select Miruro playback and caption providers

Checks/resolved-playback.py

@@ -20,7 +20,11 @@ class Handler(http.server.BaseHTTPRequestHandler):
     def do_GET(self):
         path = urlsplit(self.path).path
         seen.append(path)
-        expected = "subtitle-private" if path == "/english.jpeg" else "stream-private"
+        alternate = path.startswith("/alternate/")
+        captions = path.startswith("/captions/")
+        if alternate or captions:
+            path = "/" + path.split("/", 2)[2]
+        expected = "alternate-private" if alternate else "subtitle-private" if captions or path == "/english.jpeg" else "stream-private"
         if self.headers.get("X-Resource") != expected:
             errors.append("wrong resource headers: " + path)
             self.send_error(403)
@@ -34,7 +38,8 @@ class Handler(http.server.BaseHTTPRequestHandler):
                 errors.append("variant token lost")
             data = (fixtures / "resolved-vod.m3u8").read_bytes()
         elif path == "/english.jpeg":
-            data = b'WEBVTT\n\n00:00.000 --> 00:02.000\nFirst English cue\n\n00:02.000 --> 00:04.000\nSecond English cue\n'
+            data = (b'WEBVTT\n\n00:00.000 --> 00:10.000\nAlternate English cue\n' if alternate else
+                    b'WEBVTT\n\n00:00.000 --> 00:02.000\nFirst English cue\n\n00:02.000 --> 00:04.000\nSecond English cue\n')
         elif path.startswith("/resolved-vod-") and path.endswith(".ts"):
             data = (fixtures / path[1:]).read_bytes()
         else:
@@ -71,6 +76,7 @@ try:
         assert "stream-private" not in progress.read_text() and "token=" not in progress.read_text(), "progress has no transport secrets"
     assert not errors, errors
     assert {"/master.m3u8", "/variant.m3u8", "/english.jpeg"}.issubset(seen), "master, nested playlist and external VTT fetched"
+    assert {"/alternate/master.m3u8", "/alternate/english.jpeg"}.issubset(seen), "alternate video host and independent caption provider fetched"
     assert any(path.endswith(".ts") for path in seen), "media segment fetched"
     print("PASS: model HLS/VTT playback, independent resource headers, tokens, stable progress")
 finally: