refactor: extract common code from aaredaq

tests/test_diffraction_geometry.py

@@ -0,0 +1,68 @@
+import pytest
+from aarecommon.math.diffraction_geometry import DiffractionGeometry
+
+
+@pytest.fixture
+def sample_dg():
+    return DiffractionGeometry(
+        energy_keV=12.4,
+        dtz_mm=100.0,
+        pixel_size_mm=0.172,
+        beam_center_pxl=(1000.0, 1000.0),
+        detector_size_pxl=(2000, 2000),
+        detector_description="Eiger 16M",
+        detector_serial_number="E-123",
+        poni_rot1_rad=0.0,
+        poni_rot2_rad=0.0,
+    )
+
+
+def test_detector_max_radius_pxl(sample_dg):
+    # center (1000, 1000), size (2000, 2000)
+    # x0 = 2000-1000 = 1000
+    # x1 = 1000
+    # y0 = 2000-1000 = 1000
+    # y1 = 1000
+    # max = 1000
+    assert sample_dg.detector_max_radius_pxl == 1000.0
+
+
+def test_detector_radius_mm(sample_dg):
+    # 1000 * 0.172 = 172.0
+    assert sample_dg.detector_radius_mm == 172.0
+
+
+def test_wavelength_angstrom(sample_dg):
+    # 12.398 / 12.4 = 0.9998387...
+    assert sample_dg.wavelength_angstrom == pytest.approx(0.9998387)
+
+
+def test_resolution_angstrom(sample_dg):
+    # dtz = 100
+    # radius = 172
+    # theta = atan(172/100) * 0.5 = atan(1.72) * 0.5 = 1.044 * 0.5 = 0.522 rad
+    # res = 0.9998 / (2 * sin(0.522)) = 0.9998 / (2 * 0.498) = 1.003
+    res = sample_dg.resolution_angstrom(100.0)
+    assert res > 0
+    assert res == pytest.approx(1.002469, abs=1e-5)
+
+    with pytest.raises(ValueError):
+        sample_dg.resolution_angstrom(0)
+
+
+def test_max_resolution_angstrom(sample_dg):
+    assert sample_dg.max_resolution_angstrom == sample_dg.resolution_angstrom(
+        sample_dg.dtz_mm
+    )
+
+
+def test_calc_dtz_mm(sample_dg):
+    res = sample_dg.resolution_angstrom(100.0)
+    dtz = sample_dg.calc_dtz_mm(res)
+    assert dtz == pytest.approx(100.0)
+
+    with pytest.raises(ValueError):
+        sample_dg.calc_dtz_mm(-1)
+
+    # test x >= 1.0 case: wavelength / (2*res) >= 1.0 -> res <= wavelength / 2
+    assert sample_dg.calc_dtz_mm(0.0001) == 0.0