diff --git a/.azure-pipelines/azure-pipelines-base.yml b/.azure-pipelines/azure-pipelines-base.yml
index a3eff465f9..53cb1ef709 100644
--- a/.azure-pipelines/azure-pipelines-base.yml
+++ b/.azure-pipelines/azure-pipelines-base.yml
@@ -5,6 +5,8 @@ jobs:
   variables:
     - name: NUMBA_DISABLE_JIT
       value: 1
+    - name: ARVIZ_CI_MACHINE
+      value: 1
   timeoutInMinutes: 360
   strategy:
     matrix:
diff --git a/.azure-pipelines/azure-pipelines-external.yml b/.azure-pipelines/azure-pipelines-external.yml
index 67542506b6..12afd50c50 100644
--- a/.azure-pipelines/azure-pipelines-external.yml
+++ b/.azure-pipelines/azure-pipelines-external.yml
@@ -5,6 +5,8 @@ jobs:
   variables:
     - name: NUMBA_DISABLE_JIT
       value: 1
+    - name: ARVIZ_CI_MACHINE
+      value: 1
   timeoutInMinutes: 360
   strategy:
     matrix:
diff --git a/.gitignore b/.gitignore
index 9e50d2b96d..f4fca72d24 100644
--- a/.gitignore
+++ b/.gitignore
@@ -62,6 +62,7 @@ target/
 
 # IDE configs
 .idea/
+.vscode/
 
 saved_animations/
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 75cad75182..b2bf074d13 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@
 * Add `num_chains` and `pred_dims` arguments to io_pyro #1090
 * Integrate jointplot into pairplot, add point-estimate and overlay of plot kinds (#1079)
 * Allow xarray.Dataarray input for plots.(#1120)
+* Skip test for optional/extra dependencies when not installed (#1113)
 ### Maintenance and fixes
 * Fixed behaviour of `credible_interval=None` in `plot_posterior` (#1115)
 * Fixed hist kind of `plot_dist` with multidimensional input (#1115)
@@ -212,4 +213,3 @@
 ## v0.3.0 (2018 Dec 14)
 
 * First Beta Release
-
diff --git a/arviz/tests/base_tests/test_diagnostics.py b/arviz/tests/base_tests/test_diagnostics.py
index 102510bcec..01b1f0d65f 100644
--- a/arviz/tests/base_tests/test_diagnostics.py
+++ b/arviz/tests/base_tests/test_diagnostics.py
@@ -1,28 +1,28 @@
 """Test Diagnostic methods"""
 # pylint: disable=redefined-outer-name, no-member, too-many-public-methods
 import os
+
 import numpy as np
-from numpy.testing import assert_almost_equal, assert_array_almost_equal
 import pandas as pd
 import pytest
+from numpy.testing import assert_almost_equal, assert_array_almost_equal
 
-from ...data import load_arviz_data, from_cmdstan
+from ...data import from_cmdstan, load_arviz_data
 from ...plots.plot_utils import xarray_var_iter
-from ...stats import bfmi, rhat, ess, mcse, geweke
+from ...rcparams import rcParams
+from ...stats import bfmi, ess, geweke, mcse, rhat
 from ...stats.diagnostics import (
-    ks_summary,
+    _conv_quantile,
     _ess,
     _ess_quantile,
-    _multichain_statistics,
     _mc_error,
+    _multichain_statistics,
     _rhat,
     _rhat_rank,
-    _z_scale,
-    _conv_quantile,
     _split_chains,
+    _z_scale,
+    ks_summary,
 )
-from ...utils import Numba
-from ...rcparams import rcParams
 
 # For tests only, recommended value should be closer to 1.01-1.05
 # See discussion in https://github.com/stan-dev/rstan/pull/618
@@ -536,85 +536,3 @@ def test_split_chain_dims(self, chains, draws):
         if chains is None:
             chains = 1
         assert split_data.shape == (chains * 2, draws // 2)
-
-
-def test_numba_bfmi():
-    """Numba test for bfmi."""
-    state = Numba.numba_flag
-    school = load_arviz_data("centered_eight")
-    data_md = np.random.rand(100, 100, 10)
-    Numba.disable_numba()
-    non_numba = bfmi(school.posterior["mu"].values)
-    non_numba_md = bfmi(data_md)
-    Numba.enable_numba()
-    with_numba = bfmi(school.posterior["mu"].values)
-    with_numba_md = bfmi(data_md)
-    assert np.allclose(non_numba_md, with_numba_md)
-    assert np.allclose(with_numba, non_numba)
-    assert state == Numba.numba_flag
-
-
-@pytest.mark.parametrize("method", ("rank", "split", "folded", "z_scale", "identity"))
-def test_numba_rhat(method):
-    """Numba test for mcse."""
-    state = Numba.numba_flag
-    school = np.random.rand(100, 100)
-    Numba.disable_numba()
-    non_numba = rhat(school, method=method)
-    Numba.enable_numba()
-    with_numba = rhat(school, method=method)
-    assert np.allclose(with_numba, non_numba)
-    assert Numba.numba_flag == state
-
-
-@pytest.mark.parametrize("method", ("mean", "sd", "quantile"))
-def test_numba_mcse(method, prob=None):
-    """Numba test for mcse."""
-    state = Numba.numba_flag
-    school = np.random.rand(100, 100)
-    if method == "quantile":
-        prob = 0.80
-    Numba.disable_numba()
-    non_numba = mcse(school, method=method, prob=prob)
-    Numba.enable_numba()
-    with_numba = mcse(school, method=method, prob=prob)
-    assert np.allclose(with_numba, non_numba)
-    assert Numba.numba_flag == state
-
-
-def test_ks_summary_numba():
-    """Numba test for ks_summary."""
-    state = Numba.numba_flag
-    data = np.random.randn(100, 100)
-    Numba.disable_numba()
-    non_numba = (ks_summary(data)["Count"]).values
-    Numba.enable_numba()
-    with_numba = (ks_summary(data)["Count"]).values
-    assert np.allclose(non_numba, with_numba)
-    assert Numba.numba_flag == state
-
-
-def test_geweke_numba():
-    """Numba test for geweke."""
-    state = Numba.numba_flag
-    data = np.random.randn(100)
-    Numba.disable_numba()
-    non_numba = geweke(data)
-    Numba.enable_numba()
-    with_numba = geweke(data)
-    assert np.allclose(non_numba, with_numba)
-    assert Numba.numba_flag == state
-
-
-@pytest.mark.parametrize("batches", (1, 20))
-@pytest.mark.parametrize("circular", (True, False))
-def test_mcse_error_numba(batches, circular):
-    """Numba test for mcse_error."""
-    data = np.random.randn(100, 100)
-    state = Numba.numba_flag
-    Numba.disable_numba()
-    non_numba = _mc_error(data, batches=batches, circular=circular)
-    Numba.enable_numba()
-    with_numba = _mc_error(data, batches=batches, circular=circular)
-    assert np.allclose(non_numba, with_numba)
-    assert state == Numba.numba_flag
diff --git a/arviz/tests/base_tests/test_diagnostics_numba.py b/arviz/tests/base_tests/test_diagnostics_numba.py
new file mode 100644
index 0000000000..71bce25ae9
--- /dev/null
+++ b/arviz/tests/base_tests/test_diagnostics_numba.py
@@ -0,0 +1,104 @@
+"""Test Diagnostic methods"""
+import importlib
+
+# pylint: disable=redefined-outer-name, no-member, too-many-public-methods
+import numpy as np
+import pytest
+
+from ...data import load_arviz_data
+from ..helpers import running_on_ci
+from ...rcparams import rcParams
+from ...stats import bfmi, geweke, mcse, rhat
+from ...stats.diagnostics import _mc_error, ks_summary
+from ...utils import Numba
+from .test_diagnostics import data  # pylint: disable=unused-import
+
+
+pytestmark = pytest.mark.skipif(  # pylint: disable=invalid-name
+    (importlib.util.find_spec("numba") is None) & ~running_on_ci(),
+    reason="test requires numba which is not installed",
+)
+
+rcParams["data.load"] = "eager"
+
+
+def test_numba_bfmi():
+    """Numba test for bfmi."""
+    state = Numba.numba_flag
+    school = load_arviz_data("centered_eight")
+    data_md = np.random.rand(100, 100, 10)
+    Numba.disable_numba()
+    non_numba = bfmi(school.posterior["mu"].values)
+    non_numba_md = bfmi(data_md)
+    Numba.enable_numba()
+    with_numba = bfmi(school.posterior["mu"].values)
+    with_numba_md = bfmi(data_md)
+    assert np.allclose(non_numba_md, with_numba_md)
+    assert np.allclose(with_numba, non_numba)
+    assert state == Numba.numba_flag
+
+
+@pytest.mark.parametrize("method", ("rank", "split", "folded", "z_scale", "identity"))
+def test_numba_rhat(method):
+    """Numba test for mcse."""
+    state = Numba.numba_flag
+    school = np.random.rand(100, 100)
+    Numba.disable_numba()
+    non_numba = rhat(school, method=method)
+    Numba.enable_numba()
+    with_numba = rhat(school, method=method)
+    assert np.allclose(with_numba, non_numba)
+    assert Numba.numba_flag == state
+
+
+@pytest.mark.parametrize("method", ("mean", "sd", "quantile"))
+def test_numba_mcse(method, prob=None):
+    """Numba test for mcse."""
+    state = Numba.numba_flag
+    school = np.random.rand(100, 100)
+    if method == "quantile":
+        prob = 0.80
+    Numba.disable_numba()
+    non_numba = mcse(school, method=method, prob=prob)
+    Numba.enable_numba()
+    with_numba = mcse(school, method=method, prob=prob)
+    assert np.allclose(with_numba, non_numba)
+    assert Numba.numba_flag == state
+
+
+def test_ks_summary_numba():
+    """Numba test for ks_summary."""
+    state = Numba.numba_flag
+    data = np.random.randn(100, 100)
+    Numba.disable_numba()
+    non_numba = (ks_summary(data)["Count"]).values
+    Numba.enable_numba()
+    with_numba = (ks_summary(data)["Count"]).values
+    assert np.allclose(non_numba, with_numba)
+    assert Numba.numba_flag == state
+
+
+def test_geweke_numba():
+    """Numba test for geweke."""
+    state = Numba.numba_flag
+    data = np.random.randn(100)
+    Numba.disable_numba()
+    non_numba = geweke(data)
+    Numba.enable_numba()
+    with_numba = geweke(data)
+    assert np.allclose(non_numba, with_numba)
+    assert Numba.numba_flag == state
+
+
+@pytest.mark.parametrize("batches", (1, 20))
+@pytest.mark.parametrize("circular", (True, False))
+def test_mcse_error_numba(batches, circular):
+    """Numba test for mcse_error."""
+    data = np.random.randn(100, 100)
+    state = Numba.numba_flag
+    Numba.disable_numba()
+    non_numba = _mc_error(data, batches=batches, circular=circular)
+    Numba.enable_numba()
+    with_numba = _mc_error(data, batches=batches, circular=circular)
+    assert np.allclose(non_numba, with_numba)
+    assert state == Numba.numba_flag
diff --git a/arviz/tests/base_tests/test_helpers.py b/arviz/tests/base_tests/test_helpers.py
new file mode 100644
index 0000000000..a7d82be96f
--- /dev/null
+++ b/arviz/tests/base_tests/test_helpers.py
@@ -0,0 +1,18 @@
+import pytest
+from _pytest.outcomes import Skipped
+
+from ..helpers import importorskip
+
+
+def test_importorskip_local(monkeypatch):
+    """Test ``importorskip`` run on local machine with non-existent module, which should skip."""
+    monkeypatch.delenv("ARVIZ_CI_MACHINE", raising=False)
+    with pytest.raises(Skipped):
+        importorskip("non-existent-function")
+
+
+def test_importorskip_ci(monkeypatch):
+    """Test ``importorskip`` run on CI machine with non-existent module, which should fail."""
+    monkeypatch.setenv("ARVIZ_CI_MACHINE", 1)
+    with pytest.raises(ModuleNotFoundError):
+        importorskip("non-existent-function")
diff --git a/arviz/tests/base_tests/test_plot_utils.py b/arviz/tests/base_tests/test_plot_utils.py
index e11acf3f53..9250f84ae5 100644
--- a/arviz/tests/base_tests/test_plot_utils.py
+++ b/arviz/tests/base_tests/test_plot_utils.py
@@ -1,19 +1,22 @@
 # pylint: disable=redefined-outer-name
+import importlib
+
 import numpy as np
-import xarray as xr
 import pytest
+import xarray as xr
 
 from ...data import from_dict
+from ..helpers import running_on_ci
 from ...plots.plot_utils import (
-    make_2d,
-    xarray_to_ndarray,
-    xarray_var_iter,
-    get_bins,
-    get_coords,
     filter_plotters_list,
     format_sig_figs,
+    get_bins,
+    get_coords,
     get_plotting_function,
+    make_2d,
     matplotlib_kwarg_dealiaser,
+    xarray_to_ndarray,
+    xarray_var_iter,
 )
 from ...rcparams import rc_context
 
@@ -194,6 +197,10 @@ def test_filter_plotter_list_warning():
     assert len(plotters_filtered) == 5
 
 
+@pytest.mark.skipif(
+    (importlib.util.find_spec("bokeh") is None) & ~running_on_ci(),
+    reason="test requires bokeh which is not installed",
+)
 def test_bokeh_import():
     """Tests that correct method is returned on bokeh import"""
     plot = get_plotting_function("plot_dist", "distplot", "bokeh")
diff --git a/arviz/tests/base_tests/test_plots_bokeh.py b/arviz/tests/base_tests/test_plots_bokeh.py
index e961f3d8bc..b1452cba6e 100644
--- a/arviz/tests/base_tests/test_plots_bokeh.py
+++ b/arviz/tests/base_tests/test_plots_bokeh.py
@@ -1,21 +1,22 @@
 """Tests use the 'bokeh' backend."""
 # pylint: disable=redefined-outer-name,too-many-lines
 from copy import deepcopy
-import bokeh.plotting as bkp
-from pandas import DataFrame
+
 import numpy as np
 import pytest
+from pandas import DataFrame  # pylint: disable=wrong-import-position
 
-from ...data import from_dict, load_arviz_data
-from ..helpers import (  # pylint: disable=unused-import
+from ...data import from_dict, load_arviz_data  # pylint: disable=wrong-import-position
+from ..helpers import (  # pylint: disable=unused-import, wrong-import-position
+    create_model,
+    create_multidimensional_model,
     eight_schools_params,
+    importorskip,
     models,
-    create_model,
     multidim_models,
-    create_multidimensional_model,
 )
-from ...rcparams import rcParams, rc_context
-from ...plots import (
+from ...rcparams import rc_context, rcParams  # pylint: disable=wrong-import-position
+from ...plots import (  # pylint: disable=wrong-import-position
     plot_autocorr,
     plot_compare,
     plot_density,
@@ -31,14 +32,18 @@
     plot_loo_pit,
     plot_mcse,
     plot_pair,
-    plot_rank,
-    plot_trace,
     plot_parallel,
     plot_posterior,
     plot_ppc,
+    plot_rank,
+    plot_trace,
     plot_violin,
 )
-from ...stats import compare, loo, waic
+from ...stats import compare, loo, waic  # pylint: disable=wrong-import-position
+
+# Skip tests if bokeh not installed
+bkp = importorskip("bokeh.plotting")  # pylint: disable=invalid-name
+
 
 rcParams["data.load"] = "eager"
 
diff --git a/arviz/tests/base_tests/test_plots_matplotlib.py b/arviz/tests/base_tests/test_plots_matplotlib.py
index cd2af18a0a..d6143b6786 100644
--- a/arviz/tests/base_tests/test_plots_matplotlib.py
+++ b/arviz/tests/base_tests/test_plots_matplotlib.py
@@ -153,12 +153,8 @@ def test_plot_trace(models, kwargs):
     assert axes.shape
 
 
-@pytest.mark.parametrize(
-    "compact", [True, False],
-)
-@pytest.mark.parametrize(
-    "combined", [True, False],
-)
+@pytest.mark.parametrize("compact", [True, False])
+@pytest.mark.parametrize("combined", [True, False])
 def test_plot_trace_legend(compact, combined):
     idata = load_arviz_data("rugby")
     axes = plot_trace(
diff --git a/arviz/tests/base_tests/test_stats.py b/arviz/tests/base_tests/test_stats.py
index ab38aea502..b1cebd47ff 100644
--- a/arviz/tests/base_tests/test_stats.py
+++ b/arviz/tests/base_tests/test_stats.py
@@ -1,30 +1,28 @@
 # pylint: disable=redefined-outer-name, no-member
 from copy import deepcopy
+
 import numpy as np
-from numpy.testing import assert_allclose, assert_array_almost_equal, assert_array_equal
 import pytest
+from numpy.testing import assert_allclose, assert_array_almost_equal, assert_array_equal
 from scipy.stats import linregress
-from xarray import Dataset, DataArray
+from xarray import DataArray, Dataset
 
-
-from ...data import load_arviz_data, from_dict, convert_to_inference_data, concat
+from ...data import concat, convert_to_inference_data, from_dict, load_arviz_data
+from ...rcparams import rcParams
 from ...stats import (
+    apply_test_function,
     compare,
+    ess,
     hpd,
     loo,
-    r2_score,
-    waic,
+    loo_pit,
     psislw,
+    r2_score,
     summary,
-    loo_pit,
-    ess,
-    apply_test_function,
+    waic,
 )
 from ...stats.stats import _gpinv
-from ...utils import Numba
 from ..helpers import check_multiple_attrs, multidim_models  # pylint: disable=unused-import
-from ...rcparams import rcParams
-
 
 rcParams["data.load"] = "eager"
 
@@ -154,16 +152,6 @@ def test_summary_var_names(centered_eight, var_names_expected):
     assert len(summary_df.index) == expected
 
 
-@pytest.mark.parametrize("include_circ", [True, False])
-def test_summary_include_circ(centered_eight, include_circ):
-    assert summary(centered_eight, include_circ=include_circ) is not None
-    state = Numba.numba_flag
-    Numba.disable_numba()
-    assert summary(centered_eight, include_circ=include_circ) is not NotImplementedError
-    Numba.enable_numba()
-    assert state == Numba.numba_flag
-
-
 METRICS_NAMES = [
     "mean",
     "sd",
@@ -630,21 +618,3 @@ def test_apply_test_function_should_overwrite_error(centered_eight):
     """Test error when overwrite=False but out_name is already a present variable."""
     with pytest.raises(ValueError, match="Should overwrite"):
         apply_test_function(centered_eight, lambda y, theta: y, out_name_data="obs")
-
-
-def test_numba_stats():
-    """Numba test for r2_score"""
-    state = Numba.numba_flag  # Store the current state of Numba
-    set_1 = np.random.randn(100, 100)
-    set_2 = np.random.randn(100, 100)
-    set_3 = np.random.rand(100)
-    set_4 = np.random.rand(100)
-    Numba.disable_numba()
-    non_numba = r2_score(set_1, set_2)
-    non_numba_one_dimensional = r2_score(set_3, set_4)
-    Numba.enable_numba()
-    with_numba = r2_score(set_1, set_2)
-    with_numba_one_dimensional = r2_score(set_3, set_4)
-    assert state == Numba.numba_flag  # Ensure that inital state = final state
-    assert np.allclose(non_numba, with_numba)
-    assert np.allclose(non_numba_one_dimensional, with_numba_one_dimensional)
diff --git a/arviz/tests/base_tests/test_stats_numba.py b/arviz/tests/base_tests/test_stats_numba.py
new file mode 100644
index 0000000000..a2d135fc68
--- /dev/null
+++ b/arviz/tests/base_tests/test_stats_numba.py
@@ -0,0 +1,50 @@
+# pylint: disable=redefined-outer-name, no-member
+import importlib
+
+import numpy as np
+import pytest
+
+from ...rcparams import rcParams
+from ...stats import r2_score, summary
+from ...utils import Numba
+from ..helpers import (  # pylint: disable=unused-import
+    check_multiple_attrs,
+    multidim_models,
+    running_on_ci,
+)
+from .test_stats import centered_eight, non_centered_eight  # pylint: disable=unused-import
+
+pytestmark = pytest.mark.skipif(  # pylint: disable=invalid-name
+    (importlib.util.find_spec("numba") is None) & ~running_on_ci(),
+    reason="test requires numba which is not installed",
+)
+
+rcParams["data.load"] = "eager"
+
+
+@pytest.mark.parametrize("include_circ", [True, False])
+def test_summary_include_circ(centered_eight, include_circ):
+    assert summary(centered_eight, include_circ=include_circ) is not None
+    state = Numba.numba_flag
+    Numba.disable_numba()
+    assert summary(centered_eight, include_circ=include_circ) is not NotImplementedError
+    Numba.enable_numba()
+    assert state == Numba.numba_flag
+
+
+def test_numba_stats():
+    """Numba test for r2_score"""
+    state = Numba.numba_flag  # Store the current state of Numba
+    set_1 = np.random.randn(100, 100)
+    set_2 = np.random.randn(100, 100)
+    set_3 = np.random.rand(100)
+    set_4 = np.random.rand(100)
+    Numba.disable_numba()
+    non_numba = r2_score(set_1, set_2)
+    non_numba_one_dimensional = r2_score(set_3, set_4)
+    Numba.enable_numba()
+    with_numba = r2_score(set_1, set_2)
+    with_numba_one_dimensional = r2_score(set_3, set_4)
+    assert state == Numba.numba_flag  # Ensure that inital state = final state
+    assert np.allclose(non_numba, with_numba)
+    assert np.allclose(non_numba_one_dimensional, with_numba_one_dimensional)
diff --git a/arviz/tests/base_tests/test_utils.py b/arviz/tests/base_tests/test_utils.py
index 6160d808f4..2c9456bd32 100644
--- a/arviz/tests/base_tests/test_utils.py
+++ b/arviz/tests/base_tests/test_utils.py
@@ -3,15 +3,11 @@
 """
 # pylint: disable=redefined-outer-name, no-member
 from unittest.mock import Mock
-import importlib
 import numpy as np
 import pytest
 
 from ...utils import (
     _var_names,
-    numba_check,
-    Numba,
-    _numba_var,
     _stack,
     one_de,
     two_de,
@@ -19,7 +15,6 @@
     flatten_inference_data_to_dict,
 )
 from ...data import load_arviz_data, from_dict
-from ...stats.stats_utils import stats_variance_2d as svar
 
 
 @pytest.fixture(scope="session")
@@ -81,16 +76,6 @@ def utils_with_numba_import_fail(monkeypatch):
     return utils
 
 
-def test_utils_fixture(utils_with_numba_import_fail):
-    """Test of utils fixture to ensure mock is applied correctly"""
-
-    # If Numba doesn't exist in dev environment this will raise an ImportError
-    import numba  # pylint: disable=unused-import,W0612
-
-    with pytest.raises(ImportError):
-        utils_with_numba_import_fail.importlib.import_module("numba")
-
-
 def test_conditional_jit_decorator_no_numba(utils_with_numba_import_fail):
     """Tests to see if Numba jit code block is skipped with Import Failure
 
@@ -134,31 +119,6 @@ def func():
     assert func()
 
 
-def test_conditional_jit_numba_decorator_keyword(monkeypatch):
-    """Checks else statement and JIT keyword argument"""
-    from arviz import utils
-
-    # Mock import lib to return numba with hit method which returns a function that returns kwargs
-    numba_mock = Mock()
-    monkeypatch.setattr(utils.importlib, "import_module", lambda x: numba_mock)
-
-    def jit(**kwargs):
-        """overwrite numba.jit function"""
-        return lambda fn: lambda: (fn(), kwargs)
-
-    numba_mock.jit = jit
-
-    @utils.conditional_jit(keyword_argument="A keyword argument")
-    def placeholder_func():
-        """This function does nothing"""
-        return "output"
-
-    # pylint: disable=unpacking-non-sequence
-    function_results, wrapper_result = placeholder_func()
-    assert wrapper_result == {"keyword_argument": "A keyword argument"}
-    assert function_results == "output"
-
-
 def test_conditional_vect_numba_decorator():
     """Tests to see if Numba is used.
 
@@ -201,44 +161,6 @@ def placeholder_func():
     assert function_results == "output"
 
 
-def test_numba_check():
-    """Test for numba_check"""
-    numba = importlib.util.find_spec("numba")
-    flag = numba is not None
-    assert flag == numba_check()
-
-
-def test_numba_utils():
-    """Test for class Numba."""
-    flag = Numba.numba_flag
-    assert flag == numba_check()
-    Numba.disable_numba()
-    val = Numba.numba_flag
-    assert not val
-    Numba.enable_numba()
-    val = Numba.numba_flag
-    assert val
-    assert flag == Numba.numba_flag
-
-
-@pytest.mark.parametrize("axis", (0, 1))
-@pytest.mark.parametrize("ddof", (0, 1))
-def test_numba_var(axis, ddof):
-    """Method to test numba_var."""
-    flag = Numba.numba_flag
-    data_1 = np.random.randn(100, 100)
-    data_2 = np.random.rand(100)
-    with_numba_1 = _numba_var(svar, np.var, data_1, axis=axis, ddof=ddof)
-    with_numba_2 = _numba_var(svar, np.var, data_2, ddof=ddof)
-    Numba.disable_numba()
-    non_numba_1 = _numba_var(svar, np.var, data_1, axis=axis, ddof=ddof)
-    non_numba_2 = _numba_var(svar, np.var, data_2, ddof=ddof)
-    Numba.enable_numba()
-    assert flag == Numba.numba_flag
-    assert np.allclose(with_numba_1, non_numba_1)
-    assert np.allclose(with_numba_2, non_numba_2)
-
-
 def test_stack():
     x = np.random.randn(10, 4, 6)
     y = np.random.randn(100, 4, 6)
diff --git a/arviz/tests/base_tests/test_utils_numba.py b/arviz/tests/base_tests/test_utils_numba.py
new file mode 100644
index 0000000000..81b59a1381
--- /dev/null
+++ b/arviz/tests/base_tests/test_utils_numba.py
@@ -0,0 +1,97 @@
+"""
+Tests for arviz.utils.
+"""
+import importlib
+
+# pylint: disable=redefined-outer-name, no-member
+from unittest.mock import Mock
+
+import numpy as np
+import pytest
+
+from ..helpers import running_on_ci
+from ...stats.stats_utils import stats_variance_2d as svar
+from ...utils import (
+    Numba,
+    _numba_var,
+    numba_check,
+)
+from .test_utils import utils_with_numba_import_fail  # pylint: disable=unused-import
+
+pytestmark = pytest.mark.skipif(  # pylint: disable=invalid-name
+    (importlib.util.find_spec("numba") is None) & ~running_on_ci(),
+    reason="test requires numba which is not installed",
+)
+
+
+def test_utils_fixture(utils_with_numba_import_fail):
+    """Test of utils fixture to ensure mock is applied correctly"""
+
+    # If Numba doesn't exist in dev environment this will raise an ImportError
+    import numba  # pylint: disable=unused-import,W0612
+
+    with pytest.raises(ImportError):
+        utils_with_numba_import_fail.importlib.import_module("numba")
+
+
+def test_conditional_jit_numba_decorator_keyword(monkeypatch):
+    """Checks else statement and JIT keyword argument"""
+    from arviz import utils
+
+    # Mock import lib to return numba with hit method which returns a function that returns kwargs
+    numba_mock = Mock()
+    monkeypatch.setattr(utils.importlib, "import_module", lambda x: numba_mock)
+
+    def jit(**kwargs):
+        """overwrite numba.jit function"""
+        return lambda fn: lambda: (fn(), kwargs)
+
+    numba_mock.jit = jit
+
+    @utils.conditional_jit(keyword_argument="A keyword argument")
+    def placeholder_func():
+        """This function does nothing"""
+        return "output"
+
+    # pylint: disable=unpacking-non-sequence
+    function_results, wrapper_result = placeholder_func()
+    assert wrapper_result == {"keyword_argument": "A keyword argument"}
+    assert function_results == "output"
+
+
+def test_numba_check():
+    """Test for numba_check"""
+    numba = importlib.util.find_spec("numba")
+    flag = numba is not None
+    assert flag == numba_check()
+
+
+def test_numba_utils():
+    """Test for class Numba."""
+    flag = Numba.numba_flag
+    assert flag == numba_check()
+    Numba.disable_numba()
+    val = Numba.numba_flag
+    assert not val
+    Numba.enable_numba()
+    val = Numba.numba_flag
+    assert val
+    assert flag == Numba.numba_flag
+
+
+@pytest.mark.parametrize("axis", (0, 1))
+@pytest.mark.parametrize("ddof", (0, 1))
+def test_numba_var(axis, ddof):
+    """Method to test numba_var."""
+    flag = Numba.numba_flag
+    data_1 = np.random.randn(100, 100)
+    data_2 = np.random.rand(100)
+    with_numba_1 = _numba_var(svar, np.var, data_1, axis=axis, ddof=ddof)
+    with_numba_2 = _numba_var(svar, np.var, data_2, ddof=ddof)
+    Numba.disable_numba()
+    non_numba_1 = _numba_var(svar, np.var, data_1, axis=axis, ddof=ddof)
+    non_numba_2 = _numba_var(svar, np.var, data_2, ddof=ddof)
+    Numba.enable_numba()
+    assert flag == Numba.numba_flag
+    assert np.allclose(with_numba_1, non_numba_1)
+    assert np.allclose(with_numba_2, non_numba_2)
diff --git a/arviz/tests/external_tests/test_data_cmdstanpy.py b/arviz/tests/external_tests/test_data_cmdstanpy.py
index f49ed4faf7..29380e230f 100644
--- a/arviz/tests/external_tests/test_data_cmdstanpy.py
+++ b/arviz/tests/external_tests/test_data_cmdstanpy.py
@@ -12,6 +12,7 @@
     check_multiple_attrs,
     draws,
     eight_schools_params,
+    importorskip,
     load_cached_models,
     pystan_version,
 )
@@ -32,9 +33,12 @@ def filepaths(self, data_directory):
 
     @pytest.fixture(scope="class")
     def data(self, filepaths):
-        from cmdstanpy import CmdStanMCMC
-        from cmdstanpy.stanfit import RunSet
-        from cmdstanpy.model import CmdStanArgs, SamplerArgs
+        # Skip tests if cmdstanpy not installed
+        cmdstanpy = importorskip("cmdstanpy")
+        CmdStanMCMC = cmdstanpy.CmdStanMCMC  # pylint: disable=invalid-name
+        RunSet = cmdstanpy.stanfit.RunSet  # pylint: disable=invalid-name
+        CmdStanArgs = cmdstanpy.model.CmdStanArgs  # pylint: disable=invalid-name
+        SamplerArgs = cmdstanpy.model.SamplerArgs  # pylint: disable=invalid-name
 
         class Data:
             args = CmdStanArgs(
diff --git a/arviz/tests/external_tests/test_data_emcee.py b/arviz/tests/external_tests/test_data_emcee.py
index 62a33538a4..324e30dc24 100644
--- a/arviz/tests/external_tests/test_data_emcee.py
+++ b/arviz/tests/external_tests/test_data_emcee.py
@@ -3,10 +3,8 @@
 import numpy as np
 import pytest
 
-import emcee  # pylint: disable=unused-import
-
-from arviz import from_emcee
-from ..helpers import (  # pylint: disable=unused-import
+from arviz import from_emcee  # pylint: disable=wrong-import-position
+from ..helpers import (  # pylint: disable=unused-import, wrong-import-position
     chains,
     check_multiple_attrs,
     draws,
@@ -15,8 +13,12 @@
     needs_emcee3_func,
     eight_schools_params,
     load_cached_models,
+    importorskip,
 )
 
+# Skip all tests if emcee not installed
+emcee = importorskip("emcee")
+
 needs_emcee3 = needs_emcee3_func()
 
 
diff --git a/arviz/tests/external_tests/test_data_numpyro.py b/arviz/tests/external_tests/test_data_numpyro.py
index 23e53822cb..2719489043 100644
--- a/arviz/tests/external_tests/test_data_numpyro.py
+++ b/arviz/tests/external_tests/test_data_numpyro.py
@@ -1,18 +1,22 @@
 # pylint: disable=no-member, invalid-name, redefined-outer-name
 import numpy as np
 import pytest
-from jax.random import PRNGKey
-from numpyro.infer import Predictive
 
-from ...data.io_numpyro import from_numpyro
-from ..helpers import (  # pylint: disable=unused-import
+from ...data.io_numpyro import from_numpyro  # pylint: disable=wrong-import-position
+from ..helpers import (  # pylint: disable=unused-import, wrong-import-position
     chains,
     check_multiple_attrs,
     draws,
     eight_schools_params,
+    importorskip,
     load_cached_models,
 )
 
+# Skip all tests if jax or numpyro not installed
+jax = importorskip("jax")
+PRNGKey = jax.random.PRNGKey
+numpyro = importorskip("numpyro")
+Predictive = numpyro.infer.Predictive
 
 class TestDataNumPyro:
     @pytest.fixture(scope="class")
diff --git a/arviz/tests/external_tests/test_data_pymc.py b/arviz/tests/external_tests/test_data_pymc.py
index 15381bcfbc..56ae89f28f 100644
--- a/arviz/tests/external_tests/test_data_pymc.py
+++ b/arviz/tests/external_tests/test_data_pymc.py
@@ -1,22 +1,25 @@
 # pylint: disable=no-member, invalid-name, redefined-outer-name
 from sys import version_info
-from typing import Tuple, Dict
-import pytest
-
+from typing import Dict, Tuple
 
 import numpy as np
+import pytest
 from numpy import ma
-import pymc3 as pm
 
-from arviz import from_pymc3, from_pymc3_predictions, InferenceData
-from ..helpers import (  # pylint: disable=unused-import
+from arviz import from_pymc3, from_pymc3_predictions, InferenceData  # pylint: disable=wrong-import-position
+
+from ..helpers import (  # pylint: disable=unused-import, wrong-import-position
     chains,
     check_multiple_attrs,
     draws,
     eight_schools_params,
+    importorskip,
     load_cached_models,
 )
 
+# Skip all tests if pymc3 not installed
+pm = importorskip("pymc3")
+
 
 class TestDataPyMC3:
     @pytest.fixture(scope="class")
diff --git a/arviz/tests/external_tests/test_data_pyro.py b/arviz/tests/external_tests/test_data_pyro.py
index d620a17cf2..e21eb435c0 100644
--- a/arviz/tests/external_tests/test_data_pyro.py
+++ b/arviz/tests/external_tests/test_data_pyro.py
@@ -2,19 +2,22 @@
 import numpy as np
 import packaging
 import pytest
-import torch
-import pyro
-from pyro.infer import Predictive
 
-from ...data.io_pyro import from_pyro
-from ..helpers import (  # pylint: disable=unused-import
+from ...data.io_pyro import from_pyro  # pylint: disable=wrong-import-position
+from ..helpers import (  # pylint: disable=unused-import, wrong-import-position
     chains,
     check_multiple_attrs,
     draws,
     eight_schools_params,
+    importorskip,
     load_cached_models,
 )
 
+# Skip all tests if pyro or pytorch not installed
+torch = importorskip("torch")
+pyro = importorskip("pyro")
+Predictive = pyro.infer.Predictive
+
 
 class TestDataPyro:
     @pytest.fixture(scope="class")
diff --git a/arviz/tests/external_tests/test_data_pystan.py b/arviz/tests/external_tests/test_data_pystan.py
index 5f0bee08f5..7310a534f0 100644
--- a/arviz/tests/external_tests/test_data_pystan.py
+++ b/arviz/tests/external_tests/test_data_pystan.py
@@ -1,17 +1,31 @@
 # pylint: disable=no-member, invalid-name, redefined-outer-name
+import importlib
 from collections import OrderedDict
+
 import numpy as np
 import pytest
 
 from arviz import from_pystan
+
 from ...data.io_pystan import get_draws, get_draws_stan3  # pylint: disable=unused-import
 from ..helpers import (  # pylint: disable=unused-import
     chains,
     check_multiple_attrs,
     draws,
     eight_schools_params,
+    importorskip,
     load_cached_models,
     pystan_version,
+    running_on_ci,
+)
+
+# Check if either pystan or pystan3 is installed
+pystan_installed = (importlib.util.find_spec("pystan") is not None) or (
+    importlib.util.find_spec("stan") is not None
+)
+pytestmark = pytest.mark.skipif(
+    not (pystan_installed | running_on_ci()),
+    reason="test requires pystan/pystan3 which is not installed",
 )
 
 
@@ -217,7 +231,8 @@ def test_get_draws(self, data):
     @pytest.mark.skipif(pystan_version() != 2, reason="PyStan 2.x required")
     def test_index_order(self, data, eight_schools_params):
         """Test 0-indexed data."""
-        import pystan  # pylint: disable=import-error
+        # Skip test if pystan not installed
+        pystan = importorskip("pystan")  # pylint: disable=import-error
 
         fit = data.model.sampling(data=eight_schools_params)
         if pystan.__version__ >= "2.18":
diff --git a/arviz/tests/external_tests/test_data_tfp.py b/arviz/tests/external_tests/test_data_tfp.py
index 9191666639..880d8501d3 100644
--- a/arviz/tests/external_tests/test_data_tfp.py
+++ b/arviz/tests/external_tests/test_data_tfp.py
@@ -8,9 +8,13 @@
     check_multiple_attrs,
     draws,
     eight_schools_params,
+    importorskip,
     load_cached_models,
 )
 
+# Skip all tests if tensorflow_probability not installed
+importorskip("tensorflow_probability")
+
 
 class TestDataTfp:
     @pytest.fixture(scope="class")
diff --git a/arviz/tests/helpers.py b/arviz/tests/helpers.py
index 1d7b565514..ddc31b505c 100644
--- a/arviz/tests/helpers.py
+++ b/arviz/tests/helpers.py
@@ -2,16 +2,18 @@
 """Test helper functions."""
 import gzip
 import importlib
+import logging
 import os
 import pickle
 import sys
-import logging
-from typing import Dict, List, Tuple, Union
-import pytest
-import numpy as np
+from typing import Any, Dict, List, Optional, Tuple, Union
 
-from ..data import from_dict, InferenceData
+import numpy as np
+import pytest
+from _pytest.outcomes import Skipped
+from packaging.version import Version
 
+from ..data import InferenceData, from_dict
 
 _log = logging.getLogger(__name__)
 
@@ -571,11 +573,70 @@ def pystan_version():
     """
     try:
         import pystan  # pylint: disable=import-error
+
+        version = int(pystan.__version__[0])
     except ImportError:
-        import stan as pystan  # pylint: disable=import-error
-    return int(pystan.__version__[0])
+        try:
+            import stan as pystan  # pylint: disable=import-error
+
+            version = int(pystan.__version__[0])
+        except ImportError:
+            version = None
+    return version
 
 
 def test_precompile_models(eight_schools_params, draws, chains):
     """Precompile model files."""
     load_cached_models(eight_schools_params, draws, chains)
+
+
+def running_on_ci() -> bool:
+    """Return True if running on CI machine."""
+    return os.environ.get("ARVIZ_CI_MACHINE") is not None
+
+
+def importorskip(
+    modname: str, minversion: Optional[str] = None, reason: Optional[str] = None
+) -> Any:
+    """Import and return the requested module ``modname``.
+
+        Doesn't allow skips on CI machine.
+        Borrowed and modified from ``pytest.importorskip``.
+    :param str modname: the name of the module to import
+    :param str minversion: if given, the imported module's ``__version__``
+        attribute must be at least this minimal version, otherwise the test is
+        still skipped.
+    :param str reason: if given, this reason is shown as the message when the
+        module cannot be imported.
+    :returns: The imported module. This should be assigned to its canonical
+        name.
+    Example::
+        docutils = pytest.importorskip("docutils")
+    """
+    # ARVIZ_CI_MACHINE is True if tests run on CI, where ARVIZ_CI_MACHINE env variable exists
+    ARVIZ_CI_MACHINE = running_on_ci()
+    if ARVIZ_CI_MACHINE:
+        import warnings
+
+        compile(modname, "", "eval")  # to catch syntaxerrors
+
+        with warnings.catch_warnings():
+            # make sure to ignore ImportWarnings that might happen because
+            # of existing directories with the same name we're trying to
+            # import but without a __init__.py file
+            warnings.simplefilter("ignore")
+            __import__(modname)
+        mod = sys.modules[modname]
+        if minversion is None:
+            return mod
+        verattr = getattr(mod, "__version__", None)
+        if minversion is not None:
+            if verattr is None or Version(verattr) < Version(minversion):
+                raise Skipped(
+                    "module %r has __version__ %r, required is: %r"
+                    % (modname, verattr, minversion),
+                    allow_module_level=True,
+                )
+        return mod
+    else:
+        return pytest.importorskip(modname=modname, minversion=minversion, reason=reason)
diff --git a/pytest.ini b/pytest.ini
index 14b1ba1631..09e578bdc3 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -1,5 +1,5 @@
 [pytest]
-addopts = --strict -rf --durations=20 -p no:warnings
+addopts = --strict -rsf --durations=20 -p no:warnings
 console_output_style = count
 junit_family= xunit1
 markers =