diff --git a/src/emcee/tests/unit/test_ensemble.py b/src/emcee/tests/unit/test_ensemble.py
index f0568b27..274c20a7 100644
--- a/src/emcee/tests/unit/test_ensemble.py
+++ b/src/emcee/tests/unit/test_ensemble.py
@@ -1,185 +1,188 @@
-"""
-Unit tests of some functionality in ensemble.py when the parameters are named
-"""
-
-import string
-from unittest import TestCase
-
-import numpy as np
-import pytest
-
-from emcee.ensemble import EnsembleSampler, ndarray_to_list_of_dicts
-
-
-class TestNP2ListOfDicts(TestCase):
-    def test_ndarray_to_list_of_dicts(self):
-        # Try different numbers of keys
-        for n_keys in [1, 2, 10, 26]:
-            keys = list(string.ascii_lowercase[:n_keys])
-            key_set = set(keys)
-            key_dict = {key: i for i, key in enumerate(keys)}
-            # Try different number of walker/procs
-            for N in [1, 2, 3, 10, 100]:
-                x = np.random.rand(N, n_keys)
-
-                LOD = ndarray_to_list_of_dicts(x, key_dict)
-                assert len(LOD) == N, "need 1 dict per row"
-                for i, dct in enumerate(LOD):
-                    assert dct.keys() == key_set, "keys are missing"
-                    for j, key in enumerate(keys):
-                        assert dct[key] == x[i, j], f"wrong value at {(i, j)}"
-
-
-class TestNamedParameters(TestCase):
-    """
-    Test that a keyword-based log-probability function instead of
-    a positional.
-    """
-
-    # Keyword based lnpdf
-    def lnpdf(self, pars) -> np.float64:
-        mean = pars["mean"]
-        var = pars["var"]
-        if var <= 0:
-            return -np.inf
-        return (
-            -0.5 * ((mean - self.x) ** 2 / var + np.log(2 * np.pi * var)).sum()
-        )
-
-    def lnpdf_mixture(self, pars) -> np.float64:
-        mean1 = pars["mean1"]
-        var1 = pars["var1"]
-        mean2 = pars["mean2"]
-        var2 = pars["var2"]
-        if var1 <= 0 or var2 <= 0:
-            return -np.inf
-        return (
-            -0.5
-            * (
-                (mean1 - self.x) ** 2 / var1
-                + np.log(2 * np.pi * var1)
-                + (mean2 - self.x - 3) ** 2 / var2
-                + np.log(2 * np.pi * var2)
-            ).sum()
-        )
-
-    def lnpdf_mixture_grouped(self, pars) -> np.float64:
-        mean1, mean2 = pars["means"]
-        var1, var2 = pars["vars"]
-        const = pars["constant"]
-        if var1 <= 0 or var2 <= 0:
-            return -np.inf
-        return (
-            -0.5
-            * (
-                (mean1 - self.x) ** 2 / var1
-                + np.log(2 * np.pi * var1)
-                + (mean2 - self.x - 3) ** 2 / var2
-                + np.log(2 * np.pi * var2)
-            ).sum()
-            + const
-        )
-
-    def setUp(self):
-        # Draw some data from a unit Gaussian
-        self.x = np.random.randn(100)
-        self.names = ["mean", "var"]
-
-    def test_named_parameters(self):
-        sampler = EnsembleSampler(
-            nwalkers=10,
-            ndim=len(self.names),
-            log_prob_fn=self.lnpdf,
-            parameter_names=self.names,
-        )
-        assert sampler.params_are_named
-        assert list(sampler.parameter_names.keys()) == self.names
-
-    def test_asserts(self):
-        # ndim name mismatch
-        with pytest.raises(AssertionError):
-            _ = EnsembleSampler(
-                nwalkers=10,
-                ndim=len(self.names) - 1,
-                log_prob_fn=self.lnpdf,
-                parameter_names=self.names,
-            )
-
-        # duplicate names
-        with pytest.raises(AssertionError):
-            _ = EnsembleSampler(
-                nwalkers=10,
-                ndim=3,
-                log_prob_fn=self.lnpdf,
-                parameter_names=["a", "b", "a"],
-            )
-
-        # vectorize turned on
-        with pytest.raises(AssertionError):
-            _ = EnsembleSampler(
-                nwalkers=10,
-                ndim=len(self.names),
-                log_prob_fn=self.lnpdf,
-                parameter_names=self.names,
-                vectorize=True,
-            )
-
-    def test_compute_log_prob(self):
-        # Try different numbers of walkers
-        for N in [4, 8, 10]:
-            sampler = EnsembleSampler(
-                nwalkers=N,
-                ndim=len(self.names),
-                log_prob_fn=self.lnpdf,
-                parameter_names=self.names,
-            )
-            coords = np.random.rand(N, len(self.names))
-            lnps, _ = sampler.compute_log_prob(coords)
-            assert len(lnps) == N
-            assert lnps.dtype == np.float64
-
-    def test_compute_log_prob_mixture(self):
-        names = ["mean1", "var1", "mean2", "var2"]
-        # Try different numbers of walkers
-        for N in [8, 10, 20]:
-            sampler = EnsembleSampler(
-                nwalkers=N,
-                ndim=len(names),
-                log_prob_fn=self.lnpdf_mixture,
-                parameter_names=names,
-            )
-            coords = np.random.rand(N, len(names))
-            lnps, _ = sampler.compute_log_prob(coords)
-            assert len(lnps) == N
-            assert lnps.dtype == np.float64
-
-    def test_compute_log_prob_mixture_grouped(self):
-        names = {"means": [0, 1], "vars": [2, 3], "constant": 4}
-        # Try different numbers of walkers
-        for N in [8, 10, 20]:
-            sampler = EnsembleSampler(
-                nwalkers=N,
-                ndim=5,
-                log_prob_fn=self.lnpdf_mixture_grouped,
-                parameter_names=names,
-            )
-            coords = np.random.rand(N, 5)
-            lnps, _ = sampler.compute_log_prob(coords)
-            assert len(lnps) == N
-            assert lnps.dtype == np.float64
-
-    def test_run_mcmc(self):
-        # Sort of an integration test
-        n_walkers = 4
-        sampler = EnsembleSampler(
-            nwalkers=n_walkers,
-            ndim=len(self.names),
-            log_prob_fn=self.lnpdf,
-            parameter_names=self.names,
-        )
-        guess = np.random.rand(n_walkers, len(self.names))
-        n_steps = 50
-        results = sampler.run_mcmc(guess, n_steps)
-        assert results.coords.shape == (n_walkers, len(self.names))
-        chain = sampler.chain
-        assert chain.shape == (n_walkers, n_steps, len(self.names))
+"""
+Unit tests of some functionality in ensemble.py when the parameters are named
+"""
+
+import string
+import warnings
+from unittest import TestCase
+
+import numpy as np
+import pytest
+
+from emcee.ensemble import EnsembleSampler, ndarray_to_list_of_dicts
+
+
+class TestNP2ListOfDicts(TestCase):
+    def test_ndarray_to_list_of_dicts(self):
+        # Try different numbers of keys
+        for n_keys in [1, 2, 10, 26]:
+            keys = list(string.ascii_lowercase[:n_keys])
+            key_set = set(keys)
+            key_dict = {key: i for i, key in enumerate(keys)}
+            # Try different number of walker/procs
+            for N in [1, 2, 3, 10, 100]:
+                x = np.random.rand(N, n_keys)
+
+                LOD = ndarray_to_list_of_dicts(x, key_dict)
+                assert len(LOD) == N, "need 1 dict per row"
+                for i, dct in enumerate(LOD):
+                    assert dct.keys() == key_set, "keys are missing"
+                    for j, key in enumerate(keys):
+                        assert dct[key] == x[i, j], f"wrong value at {(i, j)}"
+
+
+class TestNamedParameters(TestCase):
+    """
+    Test that a keyword-based log-probability function instead of
+    a positional.
+    """
+
+    # Keyword based lnpdf
+    def lnpdf(self, pars) -> np.float64:
+        mean = pars["mean"]
+        var = pars["var"]
+        if var <= 0:
+            return -np.inf
+        return (
+            -0.5 * ((mean - self.x) ** 2 / var + np.log(2 * np.pi * var)).sum()
+        )
+
+    def lnpdf_mixture(self, pars) -> np.float64:
+        mean1 = pars["mean1"]
+        var1 = pars["var1"]
+        mean2 = pars["mean2"]
+        var2 = pars["var2"]
+        if var1 <= 0 or var2 <= 0:
+            return -np.inf
+        return (
+            -0.5
+            * (
+                (mean1 - self.x) ** 2 / var1
+                + np.log(2 * np.pi * var1)
+                + (mean2 - self.x - 3) ** 2 / var2
+                + np.log(2 * np.pi * var2)
+            ).sum()
+        )
+
+    def lnpdf_mixture_grouped(self, pars) -> np.float64:
+        mean1, mean2 = pars["means"]
+        var1, var2 = pars["vars"]
+        const = pars["constant"]
+        if var1 <= 0 or var2 <= 0:
+            return -np.inf
+        return (
+            -0.5
+            * (
+                (mean1 - self.x) ** 2 / var1
+                + np.log(2 * np.pi * var1)
+                + (mean2 - self.x - 3) ** 2 / var2
+                + np.log(2 * np.pi * var2)
+            ).sum()
+            + const
+        )
+
+    def setUp(self):
+        # Draw some data from a unit Gaussian
+        self.x = np.random.randn(100)
+        self.names = ["mean", "var"]
+
+    def test_named_parameters(self):
+        sampler = EnsembleSampler(
+            nwalkers=10,
+            ndim=len(self.names),
+            log_prob_fn=self.lnpdf,
+            parameter_names=self.names,
+        )
+        assert sampler.params_are_named
+        assert list(sampler.parameter_names.keys()) == self.names
+
+    def test_asserts(self):
+        # ndim name mismatch
+        with pytest.raises(AssertionError):
+            _ = EnsembleSampler(
+                nwalkers=10,
+                ndim=len(self.names) - 1,
+                log_prob_fn=self.lnpdf,
+                parameter_names=self.names,
+            )
+
+        # duplicate names
+        with pytest.raises(AssertionError):
+            _ = EnsembleSampler(
+                nwalkers=10,
+                ndim=3,
+                log_prob_fn=self.lnpdf,
+                parameter_names=["a", "b", "a"],
+            )
+
+        # vectorize turned on
+        with pytest.raises(AssertionError):
+            _ = EnsembleSampler(
+                nwalkers=10,
+                ndim=len(self.names),
+                log_prob_fn=self.lnpdf,
+                parameter_names=self.names,
+                vectorize=True,
+            )
+
+    def test_compute_log_prob(self):
+        # Try different numbers of walkers
+        for N in [4, 8, 10]:
+            sampler = EnsembleSampler(
+                nwalkers=N,
+                ndim=len(self.names),
+                log_prob_fn=self.lnpdf,
+                parameter_names=self.names,
+            )
+            coords = np.random.rand(N, len(self.names))
+            lnps, _ = sampler.compute_log_prob(coords)
+            assert len(lnps) == N
+            assert lnps.dtype == np.float64
+
+    def test_compute_log_prob_mixture(self):
+        names = ["mean1", "var1", "mean2", "var2"]
+        # Try different numbers of walkers
+        for N in [8, 10, 20]:
+            sampler = EnsembleSampler(
+                nwalkers=N,
+                ndim=len(names),
+                log_prob_fn=self.lnpdf_mixture,
+                parameter_names=names,
+            )
+            coords = np.random.rand(N, len(names))
+            lnps, _ = sampler.compute_log_prob(coords)
+            assert len(lnps) == N
+            assert lnps.dtype == np.float64
+
+    def test_compute_log_prob_mixture_grouped(self):
+        names = {"means": [0, 1], "vars": [2, 3], "constant": 4}
+        # Try different numbers of walkers
+        for N in [8, 10, 20]:
+            sampler = EnsembleSampler(
+                nwalkers=N,
+                ndim=5,
+                log_prob_fn=self.lnpdf_mixture_grouped,
+                parameter_names=names,
+            )
+            coords = np.random.rand(N, 5)
+            lnps, _ = sampler.compute_log_prob(coords)
+            assert len(lnps) == N
+            assert lnps.dtype == np.float64
+
+    def test_run_mcmc(self):
+        # Sort of an integration test
+        n_walkers = 4
+        sampler = EnsembleSampler(
+            nwalkers=n_walkers,
+            ndim=len(self.names),
+            log_prob_fn=self.lnpdf,
+            parameter_names=self.names,
+        )
+        guess = np.random.rand(n_walkers, len(self.names))
+        n_steps = 50
+        results = sampler.run_mcmc(guess, n_steps)
+        assert results.coords.shape == (n_walkers, len(self.names))
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", category=DeprecationWarning)
+            chain = sampler.chain
+        assert chain.shape == (n_walkers, n_steps, len(self.names))