Start adding background detect tests

tests/test_background_detectors.py

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+"""Test the scan planning algorithms of the Microscope.
+
+As well as low level function by function tests, this test suite also provides tests
+that simulate scanning a sample, checking that the expected path is followed.
+"""
+
+import re
+
+import pytest
+from pydantic import BaseModel
+import numpy as np
+
+# Just for testing importing as
+from openflexure_microscope_server.background_detect import (
+    MissingBackgroundData,
+    BackgroundDetectorStatus,
+    BackgroundDetectAlgorithm,
+    ChannelDistributions,
+    ColourChannelDetectSettings,
+    ColourChannelDetectLUV
+)
+
+RNG = np.random.default_rng()
+IMG_SHAPE = (820, 616, 3)
+BG_COLOR = [220, 215, 217]
+
+PERC_REGEX = re.compile(r"(\d+\.+\d)+%")
+
+@pytest.fixture
+def background_image():
+    image = np.ones(IMG_SHAPE, dtype=np.int16)
+    image[:, :, 0] *= BG_COLOR[0]
+    image[:, :, 1] *= BG_COLOR[1]
+    image[:, :, 2] *= BG_COLOR[2]
+    image += RNG.normal(scale=3, size=IMG_SHAPE).astype("int16")
+    image[image < 0] = 0
+    image[image > 255] = 255
+    return image.astype("uint8")
+
+@pytest.fixture
+def sample_image(background_image):
+    image = background_image.copy()
+    x_cent = IMG_SHAPE[0]//2
+    image[:x_cent,:,0] -= 180
+    return image
+
+
+def test_bg_detect_base_class():
+    """Test the base class for background detect.
+
+    If initialised as is it should raise not implemented error.
+    """
+    with pytest.raises(NotImplementedError):
+        BackgroundDetectAlgorithm()
+
+def test_partial_base_class(background_image):
+    """Create a partial class so to initialise the base class and test other methods.
+
+    This test is to check that if the necessary methods are not set, that an
+    appropriate error is raise.
+    """
+    class BadAlgo1(BackgroundDetectAlgorithm):
+        """Only has a settings model so it can initialise."""
+
+        settings_data_model: BaseModel = ColourChannelDetectSettings
+
+    bad_algo1 = BadAlgo1()
+    status = bad_algo1.status
+    assert not status.ready
+    assert isinstance(status.settings, ColourChannelDetectSettings)
+
+    with pytest.raises(NotImplementedError):
+        # Should error on any dictionary input. This simulates loading settings from
+        # disk
+        bad_algo1.background_data = {"key": 1}
+
+    with pytest.raises(NotImplementedError):
+        bad_algo1.set_background(background_image)
+
+    with pytest.raises(NotImplementedError):
+        bad_algo1.image_is_sample(background_image)
+
+def test_colour_channel_luv(background_image, sample_image):
+    cc_luv = ColourChannelDetectLUV()
+
+    # No background data so it is not ready and will error if image_is_sample is called.
+    assert not cc_luv.status.ready
+    with pytest.raises(MissingBackgroundData):
+        cc_luv.image_is_sample(background_image)
+
+    # Set the background
+    cc_luv.set_background(background_image)
+    # Now it is ready
+    assert cc_luv.status.ready
+    sample, message = cc_luv.image_is_sample(background_image)
+    assert not sample
+    assert "0.0%" in message
+    sample, message = cc_luv.image_is_sample(sample_image)
+    assert sample
+    match = PERC_REGEX.search(message)
+    assert match is not None
+    # Should be 50% background. Allowing 49.8-50.2% due to noise.
+    assert 49.8 < float(match.group(1)) < 50.2
+
+
+# TODO Save data and reload it.