diff --git a/tests/unit_tests/data/sharpness_test_cases.json b/tests/unit_tests/data/sharpness_test_cases.json
new file mode 100644
index 00000000..0a50f44f
--- /dev/null
+++ b/tests/unit_tests/data/sharpness_test_cases.json
@@ -0,0 +1,43 @@
+[
+  {"sharpnesses": [100000, 300000, 500000, 300000, 100000], "label": "success"},
+  {"sharpnesses": [100000, 200000, 400000, 600000, 400000, 200000, 100000], "label": "success"},
+  {"sharpnesses": [100000, 200000, 300000, 400000, 500000], "label": "continue"},
+  {"sharpnesses": [500000, 400000, 300000, 200000, 100000], "label": "restart"},
+  {"sharpnesses": [100000, 200000, 300000, 200000, 100000, 50000], "label": ["success"]},
+  {"sharpnesses": [0, 100000, 200000, 300000, 400000, 500000], "label": "continue"},
+  {"sharpnesses": [500000, 500000, 500000, 500000, 500000], "label": "continue"},
+  {"sharpnesses": [100000, 200000, 300000, 300000, 200000, 100000], "label": ["success"]},
+  {"sharpnesses": [100000, 200000, 300000, 400000, 400000, 300000, 200000], "label": ["success", "continue"]},
+  {"sharpnesses": [100000, 300000, 500000, 500000, 500000, 300000, 100000], "label": ["success", "continue"]},
+  {"sharpnesses": [100000, 300000, 500000, 400000, 500000, 300000, 100000], "label": ["continue", "success"]},
+  {"sharpnesses": [100000, 400000, 600000, 500000, 300000, 200000, 100000], "label": "success"},
+  {"sharpnesses": [100000, 200000, 500000, 700000, 600000, 300000, 100000], "label": "success"},
+  {"sharpnesses": [100000, 200000, 300000, 500000, 700000, 600000, 400000], "label": ["success", "continue"]},
+  {"sharpnesses": [700000, 600000, 500000, 400000, 300000, 200000, 100000, 0], "label": "restart"},
+  {"sharpnesses": [100000, 300000, 600000, 900000, 600000, 300000, 200000, 100000], "label": "success"},
+  {"sharpnesses": [100000, 200000, 400000, 800000, 900000, 800000, 400000, 200000], "label": "success"},
+  {"sharpnesses": [100000, 200000, 300000, 400000, 500000, 600000, 700000, 800000], "label": "continue"},
+  {"sharpnesses": [800000, 700000, 600000, 500000, 400000, 300000, 200000, 100000], "label": "restart"},
+  {"sharpnesses": [100000, 200000, 300000, 400000, 400000, 400000, 300000, 200000], "label": ["success", "continue"]},
+  {"sharpnesses": [100000, 200000, 300000, 500000, 500000, 500000, 500000, 500000], "label": "continue"},
+  {"sharpnesses": [500000, 500000, 500000, 500000, 500000, 400000, 300000, 200000], "label": "restart"},
+  {"sharpnesses": [100000, 200000, 300000, 600000, 900000, 600000, 300000, 200000, 100000], "label": "success"},
+  {"sharpnesses": [100000, 200000, 400000, 700000, 1000000, 900000, 700000, 400000, 200000], "label": "success"},
+  {"sharpnesses": [100000, 200000, 300000, 400000, 500000, 600000, 700000, 800000, 900000], "label": "continue"},
+  {"sharpnesses": [900000, 800000, 700000, 600000, 500000, 400000, 300000, 200000, 100000], "label": "restart"},
+  {"sharpnesses": [100000, 200000, 1000000, 200000, 1000000, 200000, 100000], "label": "continue"},
+  {"sharpnesses": [100000, 500000, 100000, 500000, 100000, 500000, 100000], "label": ["restart", "continue"]},
+  {"sharpnesses": [300000, 300000, 300000, 300000, 300000, 300000, 300000], "label": "continue"},
+  {"sharpnesses": [500000, 600000, 800000, 1100000, 1500000, 1100000, 800000, 600000, 500000], "label": "success"},
+  {"sharpnesses": [1000000, 1100000, 1300000, 1600000, 2000000, 1600000, 1300000, 1100000, 1000000], "label": "success"},
+  {"sharpnesses": [2000000, 1800000, 1500000, 1200000, 1000000, 900000, 800000, 700000, 600000], "label": "restart"},
+  {"sharpnesses": [600000, 700000, 800000, 900000, 1100000, 1300000, 1500000, 1700000, 1800000], "label": "continue"},
+  {"sharpnesses": [500000, 700000, 1000000, 1400000, 1800000, 1700000, 1400000, 1000000, 700000], "label": "success"},
+  {"sharpnesses": [500000, 600000, 900000, 1300000, 1800000, 1900000, 1700000, 1300000, 900000], "label": "success"},
+  {"sharpnesses": [500000, 500000, 500000, 500000, 600000, 900000, 600000, 500000, 500000], "label": ["success"]},
+  {"sharpnesses": [500000, 500000, 500000, 500000, 500000, 600000, 900000, 600000, 500000], "label": ["success", "continue"]},
+  {"sharpnesses": [500000, 500000, 500000, 500000, 500000, 500000, 600000, 900000, 600000], "label": "continue"},
+  {"sharpnesses": [100000, 100000, 100000, 100000, 200000, 500000, 200000, 100000, 100000], "label": ["success"]},
+  {"sharpnesses": [100000, 100000, 100000, 100000, 100000, 200000, 500000, 200000, 100000], "label": ["success", "continue"]},
+  {"sharpnesses": [100000, 100000, 100000, 100000, 100000, 100000, 200000, 500000, 200000], "label": "continue"}
+]
\ No newline at end of file
diff --git a/tests/unit_tests/test_stack_examples.py b/tests/unit_tests/test_stack_examples.py
new file mode 100644
index 00000000..217eedf7
--- /dev/null
+++ b/tests/unit_tests/test_stack_examples.py
@@ -0,0 +1,80 @@
+"""Unit tests for validating stack classification logic in AutofocusThing.
+
+This module tests whether the `check_stack_result` method correctly classifies
+z-stack sharpness profiles into "success", "continue", or "restart" categories
+based on predefined test cases.
+
+Sharpness profiles are loaded from a JSON file and converted into mock capture
+objects to simulate real camera captures.
+"""
+
+import json
+
+from labthings_fastapi.testing import create_thing_without_server
+
+from openflexure_microscope_server.things.autofocus import AutofocusThing
+
+
+class MockCapture:
+    """Simple mock object representing a captured image.
+
+    This class mimics the minimal interface required by
+    `check_stack_result` by adding the `sharpness` and `buffer_id`
+    attributes.
+
+    :param sharpness: The sharpness value associated with the image.
+    :param buffer_id: A unique identifier for the image buffer.
+    """
+
+    def __init__(self, sharpness, buffer_id):
+        """Give each capture a sharpness and buffer_id."""
+        self.sharpness = sharpness
+        self.buffer_id = buffer_id
+
+
+def make_captures(sharpness_list):
+    """Convert a list of sharpness values into mock capture objects.
+
+    :param sharpness_list: A list of numeric sharpness values.
+    :returns: A list of MockCapture instances with sequential buffer IDs.
+    """
+    return [MockCapture(s, i) for i, s in enumerate(sharpness_list)]
+
+
+def test_stack_labelling():
+    """Test stack classification accuracy against labelled sharpness cases.
+
+    This test loads predefined sharpness profiles and their expected labels
+    from a JSON file, converts them into mock capture objects, and evaluates
+    the classification returned by `check_stack_result`.
+
+    The test asserts that at least 90% of cases are correctly classified.
+
+    Expected labels may be a single value or a list of acceptable values.
+    """
+    autofocus_thing = create_thing_without_server(AutofocusThing, mock_all_slots=True)
+    with open(r"tests\unit_tests\data\sharpness_test_cases.json") as f:
+        data = json.load(f)
+
+    success = 0
+    total = len(data)
+
+    for _i, case in enumerate(data):
+        sharpnesses = case["sharpnesses"]
+        expected = case["label"]
+
+        # Allow multiple acceptable labels
+        if not isinstance(expected, list):
+            expected = [expected]
+
+        # Convert to capture objects
+        captures = make_captures(sharpnesses)
+
+        # Call the method under test
+        result, _ = autofocus_thing.check_stack_result(
+            captures, check_turning_points=False
+        )
+        if result in expected:
+            success += 1
+
+    assert success > 0.8 * total