diff --git a/selfdrive/locationd/test/test_lagd.py b/selfdrive/locationd/test/test_lagd.py
index 83232cddb2..5f03845a4e 100644
--- a/selfdrive/locationd/test/test_lagd.py
+++ b/selfdrive/locationd/test/test_lagd.py
@@ -4,7 +4,7 @@ import time
 import pytest
 
 from cereal import messaging
-from openpilot.selfdrive.locationd.lagd import LateralLagEstimator, retrieve_initial_lag, masked_normalized_cross_correlation
+from openpilot.selfdrive.locationd.lagd import LateralLagEstimator, retrieve_initial_lag, masked_normalized_cross_correlation, BLOCK_NUM_NEEDED, BLOCK_SIZE, MIN_OKAY_WINDOW_SEC
 from openpilot.selfdrive.test.process_replay.migration import migrate, migrate_carParams
 from openpilot.selfdrive.locationd.test.test_locationd_scenarios import TEST_ROUTE
 from openpilot.common.params import Params
@@ -15,16 +15,15 @@ MAX_ERR_FRAMES = 1
 DT = 0.05
 
 
-def run_estimator_on_fake_data(estimator, dt, lag_frames, n_frames, mocker):
+def process_messages(mocker, estimator, lag_frames, n_frames, vego=20.0):
   class ZeroMock(mocker.Mock):
     def __getattr__(self, *args):
       return 0
 
   for i in range(n_frames):
-    t = i * dt
-    vego = 20.0
+    t = i * estimator.dt
     desired_cuvature = np.cos(t) / (vego ** 2)
-    actual_yr = np.cos(t - lag_frames * dt) / vego
+    actual_yr = np.cos(t - lag_frames * estimator.dt) / vego
     msgs = [
       (t, "carControl", mocker.Mock(latActive=True)),
       (t, "carState", mocker.Mock(vEgo=vego, steeringPressed=False)),
@@ -77,30 +76,33 @@ class TestLagd:
     corr = masked_normalized_cross_correlation(desired_sig, actual_sig, mask, 200)[len(desired_sig) - 1:len(desired_sig) + 20]
     assert np.argmax(corr)  in range(lag_frames - MAX_ERR_FRAMES, lag_frames + MAX_ERR_FRAMES + 1)
 
+    # mask out 40% of the values, and make them noise
+    mask = np.random.choice([True, False], size=len(desired_sig), p=[0.6, 0.4])
+    desired_sig[~mask] = np.random.normal(0, 1, size=np.sum(~mask))
+    actual_sig[~mask] = np.random.normal(0, 1, size=np.sum(~mask))
+    corr = masked_normalized_cross_correlation(desired_sig, actual_sig, mask, 200)[len(desired_sig) - 1:len(desired_sig) + 20]
+    assert np.argmax(corr) in range(lag_frames - MAX_ERR_FRAMES, lag_frames + MAX_ERR_FRAMES + 1)
+
   def test_empty_estimator(self, mocker):
     mocked_CP = mocker.Mock(steerActuatorDelay=0.8)
     estimator = LateralLagEstimator(mocked_CP, DT)
     msg = estimator.get_msg(True)
     assert msg.liveDelay.status == 'unestimated'
-    assert np.allclose(msg.liveDelay.lateralDelay, 1.0)
-
-  def test_estimator(self, mocker):
-    iters = 100
-    lag_frames = random.randint(1, 19)
-
-    mocked_CP = mocker.Mock(steerActuatorDelay=1.0)
-    estimator = LateralLagEstimator(mocked_CP, DT,
-                                    block_count=10, min_valid_block_count=0,
-                                    block_size=1, okay_window_sec=iters * DT,
-                                    min_recovery_buffer_sec=0, min_yr=0)
-    run_estimator_on_fake_data(estimator, DT, lag_frames, iters, mocker)
-
-    # expect one block filled, with lateralDelayEstimate equal to lateralDelay equal to lag_frames
-    output = estimator.get_msg(True)
-    assert output.liveDelay.status == 'estimated'
-    assert np.allclose(output.liveDelay.lateralDelay, lag_frames * DT, atol=0.01)
-    assert np.allclose(output.liveDelay.lateralDelayEstimate, output.liveDelay.lateralDelay, atol=0.01)
-    assert output.liveDelay.validBlocks == 1
+    assert np.allclose(msg.liveDelay.lateralDelay, estimator.initial_lag)
+    assert np.allclose(msg.liveDelay.lateralDelayEstimate, estimator.initial_lag)
+    assert msg.liveDelay.validBlocks == 0
+
+  def test_estimator_basics(self, mocker, subtests):
+    for lag_frames in range(5):
+      with subtests.test(msg=f"lag_frames={lag_frames}"):
+        mocked_CP = mocker.Mock(steerActuatorDelay=0.8)
+        estimator = LateralLagEstimator(mocked_CP, DT, min_recovery_buffer_sec=0.0, min_yr=0.0)
+        process_messages(mocker, estimator, lag_frames, int(MIN_OKAY_WINDOW_SEC / DT) + BLOCK_NUM_NEEDED * BLOCK_SIZE)
+        msg = estimator.get_msg(True)
+        assert msg.liveDelay.status == 'estimated'
+        assert np.allclose(msg.liveDelay.lateralDelay, lag_frames * DT, atol=0.01)
+        assert np.allclose(msg.liveDelay.lateralDelayEstimate, lag_frames * DT, atol=0.01)
+        assert msg.liveDelay.validBlocks == BLOCK_NUM_NEEDED
 
   @pytest.mark.skipif(PC, reason="only on device")
   @pytest.mark.timeout(30)
@@ -117,3 +119,5 @@ class TestLagd:
       ds.append(d)
 
     assert np.mean(ds) < DT
+
+import sys
\ No newline at end of file