diff --git a/tests/unit_tests/analysis/test_adaptive_localization.py b/tests/unit_tests/analysis/test_adaptive_localization.py
new file mode 100644
index 0000000000..a87276ffe2
--- /dev/null
+++ b/tests/unit_tests/analysis/test_adaptive_localization.py
@@ -0,0 +1,104 @@
+from argparse import ArgumentParser
+from textwrap import dedent
+
+import numpy as np
+import pytest
+
+from ert.__main__ import ert_parser
+from ert.cli import ENSEMBLE_SMOOTHER_MODE
+from ert.cli.main import run_cli
+from ert.config import ErtConfig
+from ert.storage import open_storage
+
+
+def run_cli_ES_with_case(poly_config):
+    config_name = poly_config.split(".")[0]
+    prior_sample_name = "prior_sample" + "_" + config_name
+    posterior_sample_name = "posterior_sample" + "_" + config_name
+    parser = ArgumentParser(prog="test_main")
+    parsed = ert_parser(
+        parser,
+        [
+            ENSEMBLE_SMOOTHER_MODE,
+            "--current-case",
+            prior_sample_name,
+            "--target-case",
+            posterior_sample_name,
+            "--realizations",
+            "1-50",
+            poly_config,
+            "--port-range",
+            "1024-65535",
+        ],
+    )
+    run_cli(parsed)
+    storage_path = ErtConfig.from_file(poly_config).ens_path
+    with open_storage(storage_path) as storage:
+        prior_ensemble = storage.get_ensemble_by_name(prior_sample_name)
+        prior_sample = prior_ensemble.load_parameters("COEFFS")
+        posterior_ensemble = storage.get_ensemble_by_name(posterior_sample_name)
+        posterior_sample = posterior_ensemble.load_parameters("COEFFS")
+    return prior_sample, posterior_sample
+
+
+@pytest.mark.integration_test
+def test_that_adaptive_localization_with_cutoff_1_equals_ensemble_prior(copy_case):
+    copy_case("poly_example")
+    random_seed_line = "RANDOM_SEED 1234\n\n"
+    set_adaptive_localization_1 = dedent(
+        """
+        ANALYSIS_SET_VAR STD_ENKF LOCALIZATION True
+        ANALYSIS_SET_VAR STD_ENKF LOCALIZATION_CORRELATION_THRESHOLD 1.0
+        """
+    )
+
+    with open("poly.ert", "r+", encoding="utf-8") as f:
+        lines = f.readlines()
+        lines.insert(2, random_seed_line)
+        lines.insert(9, set_adaptive_localization_1)
+
+    with open("poly_localization_1.ert", "w", encoding="utf-8") as f:
+        f.writelines(lines)
+    prior_sample, posterior_sample = run_cli_ES_with_case("poly_localization_1.ert")
+
+    # Check prior and posterior samples are equal
+    assert np.allclose(posterior_sample, prior_sample)
+
+
+@pytest.mark.integration_test
+def test_that_adaptive_localization_with_cutoff_0_equals_ESupdate(copy_case):
+    """
+    Note that "RANDOM_SEED" in both ert configs needs to be the same to obtain
+    the same sample from the prior.
+    """
+    copy_case("poly_example")
+
+    random_seed_line = "RANDOM_SEED 1234\n\n"
+    set_adaptive_localization_0 = dedent(
+        """
+        ANALYSIS_SET_VAR STD_ENKF LOCALIZATION True
+        ANALYSIS_SET_VAR STD_ENKF LOCALIZATION_CORRELATION_THRESHOLD 0.0
+        """
+    )
+
+    with open("poly.ert", "r+", encoding="utf-8") as f:
+        lines = f.readlines()
+        lines.insert(2, random_seed_line)
+
+    with open("poly_no_localization.ert", "w", encoding="utf-8") as f:
+        f.writelines(lines)
+
+    lines.insert(9, set_adaptive_localization_0)
+
+    with open("poly_localization_0.ert", "w", encoding="utf-8") as f:
+        f.writelines(lines)
+
+    prior_sample_loc0, posterior_sample_loc0 = run_cli_ES_with_case(
+        "poly_localization_0.ert"
+    )
+    prior_sample_noloc, posterior_sample_noloc = run_cli_ES_with_case(
+        "poly_no_localization.ert"
+    )
+
+    # Check posterior sample without adaptive localization and with cut-off 0 are equal
+    assert np.allclose(posterior_sample_loc0, posterior_sample_noloc)