35c92e24

Add synthetic hidden-freeze regression test

a73x 2026-04-16 11:21

Commit message

Add synthetic hidden-freeze regression test

Exercises the hide → pty-flood → show sequence through the FrameLoop
state machine. Verifies no canRender() call returns true while hidden,
and that normal pacing resumes on show.

src/frame_loop.zig

@@ @@ -369,3 +369,44 @@ test "deinit destroys any pending callback" { @@
+    try std.testing.expectEqual(@as(usize, 1), mock.callbacks_destroyed);
+test "hidden-freeze regression: pty flood while hidden never blocks" {
+    var mock = try Mock.init();
+    defer mock.deinit();
+    var ts = try TestState.init(std.testing.allocator);
+    defer ts.deinit();
+    var loop = FrameLoop.init(mock.ops(), ts.view());
+    defer loop.deinit();
+    // Initial render.
+    try loop.commitRender();
+    const first_tok = loop.pending_token.?;
+    loop.onFrameCallbackDone(first_tok);
+    // Hide the surface: tracker leaves all outputs.
+    ts.tracker.leaveOutput(1);
+    loop.onSurfaceHidden();
+    try std.testing.expect(!loop.canRender());
+    // Simulate 100 iterations of "pty wrote more data, we want to render".
+    // Under the gate, canRender is false every iteration and we never call
+    // commitRender — so no Vulkan work, no blocking.
+    var i: usize = 0;
+    while (i < 100) : (i += 1) {
+        try std.testing.expect(!loop.canRender());
+    }
+    // Show again: tracker re-enters an output.
+    try ts.tracker.enterOutput(1);
+    loop.onSurfaceShown();
+    try std.testing.expect(loop.canRender());
+    // Normal render resumes.
+    try loop.commitRender();
+    try std.testing.expect(loop.pending_token != null);
+    const tok = loop.pending_token.?;
+    loop.onFrameCallbackDone(tok);
+    try std.testing.expect(loop.armed);
+}