Add tests for new simulated camera poperites that update the canvas

src/openflexure_microscope_server/things/camera/simulation.py

@@ -50,10 +50,12 @@ DOWNSAMPLE = 2
 # for a nice gain in quality.
 SPRITE_UPSAMPLE = 4
 
+# A list of 6 digit hex colour codes separated by ;. Allow a trailing ;
 COLOUR_LIST_REGEX = re.compile(
-    r"\s*^(#[0-9a-fA-F]{6})\s*(?:;\s*(#[0-9a-fA-F]{6})\s*)*$"
+    r"^\s*(#[0-9a-fA-F]{6})\s*(?:;\s*(#[0-9a-fA-F]{6})\s*)*;?\s*$"
 )
 COLOUR_REGEX = re.compile(r"^#([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})$")
+# regex to capture R, G and B
 
 
 @overload
@@ -71,7 +73,7 @@ def _downsample_shape(
         return (shape[0] // DOWNSAMPLE, shape[1] // DOWNSAMPLE)
     if len(shape) == 3:
         return (shape[0] // DOWNSAMPLE, shape[1] // DOWNSAMPLE, shape[2])
-    raise ValueError("A shape should be a 2 or 3 element tuple.")
+    raise ValueError("Shape should be a 2 or 3 element tuple.")
 
 
 def colour_str_to_colour(colour_str: str) -> tuple[int, int, int]:
@@ -80,13 +82,19 @@ def colour_str_to_colour(colour_str: str) -> tuple[int, int, int]:
     :param colour_str: Should be a hex colour such as #33aa33 or a list separated by
         semicolons.
     :return: The colour as a tuple of 3 integers from 0 to 255 in value
-    :raises ValueError: If the hex string is not valid.
+    :raises ValueError: If the hex string is not valid. This should never happen if the
+        user enters a bad colour string as the colour property setter checks the
+        whole string regex.
     """
     if ";" in colour_str:
         colours = colour_str.split(";")
-        colour_str = colours[RNG.integers(0, len(colours))]
+        if len(colours) > 1 and colours[-1].strip() == "":
-    colour_str = colour_str.lower().strip()
+            colours.pop(-1)
-    colour_match = COLOUR_REGEX.match(colour_str)
+        single_colour_str = colours[RNG.integers(0, len(colours))]
+    else:
+        single_colour_str = colour_str
+    single_colour_str = single_colour_str.lower().strip()
+    colour_match = COLOUR_REGEX.match(single_colour_str)
     if colour_match is None:
         raise ValueError(
             f"{colour_str} is not a valid colour. Please use HTML hex notation."

tests/unit_tests/test_simulated_camera.py

@@ -1,9 +1,14 @@
 """Test the functionality specific to the simulated camera."""
 
+import logging
+
 import pytest
+from hypothesis import given
+from hypothesis import strategies as st
 
 import labthings_fastapi as lt
 
+from openflexure_microscope_server.things.camera import simulation
 from openflexure_microscope_server.things.camera.simulation import SimulatedCamera
 from openflexure_microscope_server.things.stage.dummy import DummyStage
 
@@ -18,6 +23,116 @@ def test_env() -> lt.ThingClient:
         yield env
 
 
+def test_downsample_shape_2d():
+    """Test downsampling for 2D array."""
+    shape_2d = (100, 80)
+    result_2d = simulation._downsample_shape(shape_2d)
+    assert len(result_2d) == 2
+    assert result_2d == (100 // simulation.DOWNSAMPLE, 80 // simulation.DOWNSAMPLE)
+
+
+def test_downsample_shape_3d():
+    """Test downsampling for 3D array, should not affect 3rd axis or shape."""
+    shape_3d = (120, 60, 3)
+    result_3d = simulation._downsample_shape(shape_3d)
+    assert len(result_3d) == 3
+    assert result_3d == (120 // simulation.DOWNSAMPLE, 60 // simulation.DOWNSAMPLE, 3)
+
+
+def test_downsample_shape_invalid_length():
+    """Shapes that are not length 2 or 3 should raise ValueError."""
+    with pytest.raises(ValueError, match="Shape should be a 2 or 3 element tuple."):
+        simulation._downsample_shape((1,))
+
+    with pytest.raises(ValueError, match="Shape should be a 2 or 3 element tuple."):
+        simulation._downsample_shape((1, 2, 3, 4))
+
+
+def all_colours_present(
+    col_str: str, colours: list[tuple[int, int, int]], tries: int = 100
+) -> bool:
+    """Check that for a given colour string that all listed colours are returned.
+
+    A helper function for testing simulation.colour_str_to_colour. As the result is
+    randomised the test just tries multiple times. In theory could fail, so pick
+    tries high enough if there are lots of colours in col_str.
+    """
+    found = [False for _c in colours]
+    for _i in range(tries):
+        col_tuple = simulation.colour_str_to_colour(col_str)
+        if col_tuple not in colours:
+            raise ValueError("Unexpected colour returned.")
+        found[colours.index(col_tuple)] = True
+        # Don't exit early or we don't confrm that extra colours are not returned.
+    return all(found)
+
+
+def test_colour_str_to_colour():
+    """Test colour_str_to_colour with some basic predefined test cases."""
+    # A basic test
+    assert simulation.colour_str_to_colour("#123456") == (0x12, 0x34, 0x56)
+    # A basic test with a trailing semicolon and surrounding spacing
+    assert simulation.colour_str_to_colour("  #123456 ; ") == (0x12, 0x34, 0x56)
+    # A 2 colour test
+    assert all_colours_present(
+        "#123456; #654321", [(0x12, 0x34, 0x56), (0x65, 0x43, 0x21)]
+    )
+    # A failure_test (to check the helper function works!)
+    with pytest.raises(ValueError, match="Unexpected colour returned."):
+        assert all_colours_present(
+            "#123456; #654321", [(0x12, 0x34, 0x56), (0x11, 0x11, 0x11)]
+        )
+    # And some incorrect strings that should fire an error in colour_str_to_colour
+    bad_colours = ["foobar", "pink", "#123", "#123456, #654321"]
+    for colour_str in bad_colours:
+        with pytest.raises(
+            ValueError, match=r".*not a valid colour. Please use HTML hex notation."
+        ):
+            simulation.colour_str_to_colour(colour_str)
+
+
+@given(st.from_regex(simulation.COLOUR_LIST_REGEX, fullmatch=True))
+def test_colour_list_regex(colour_str):
+    """Check that anything matching the regex doesn't error when generating colours.
+
+    This will error if colour_str when splot into individual colours produces
+    # an incorrect colour. Trying 100 times for each colour_str as the returned colour
+    is randomised. Hypothesis will try to create the strings that match the regex but
+    break the test.
+    """
+    for _ in range(100):
+        simulation.colour_str_to_colour(colour_str)
+
+
+def test_canvas_regeneration(test_env, caplog):
+    """Check canvas is regenerated if blob density of colour are changed."""
+    camera = test_env.get_thing_by_type(SimulatedCamera)
+    cached_canvas = camera.canvas
+    original_colour = camera.colour
+
+    # First try a bad colour string
+    with caplog.at_level(logging.WARNING):
+        camera.colour = "foobar"
+    assert len(caplog.messages) == 1
+    assert caplog.messages[0] == "foobar is not a valid colour string."
+    # Value and canvas unchanged
+    assert camera.colour == original_colour
+    assert camera.canvas is cached_canvas
+
+    # Set a valid colour
+    camera.colour = "#123456"
+    assert camera.colour == "#123456"
+    # canvas updated
+    assert camera.canvas is not cached_canvas
+
+    # Cache again
+    cached_canvas = camera.canvas
+    camera.blob_density = 321
+    assert camera.blob_density == 321
+    # Canvas updated again
+    assert camera.canvas is not cached_canvas
+
+
 def test_simulation_cam_calibration(test_env):
     """Test that the simulated camera can be calibrated and reports calibration correctly."""
     camera = test_env.get_thing_by_type(SimulatedCamera)