start of slicing test

testing still does not work well, because `__eq__` and `__len__` have
not been implemented (properly)

tests/mixins/test_slicing.py

@@ -0,0 +1,35 @@
+import os
+import numpy as np
+import pytest
+from eitprocessing.eit_data.draeger import DraegerEITData
+
+
+environment = os.environ.get(
+    "EIT_PROCESSING_TEST_DATA",
+    os.path.abspath(os.path.dirname(os.path.dirname(__file__))),
+)
+data_directory = os.path.join(environment, "test_data")
+draeger_file1 = os.path.join(data_directory, "Draeger_Test3.bin")
+draeger_file2 = os.path.join(data_directory, "Draeger_Test.bin")
+timpel_file = os.path.join(data_directory, "Timpel_Test.txt")
+dummy_file = os.path.join(data_directory, "not_a_file.dummy")
+
+
+@pytest.fixture(scope="module")
+def draeger_data1():
+    return DraegerEITData.from_path(draeger_file1)
+
+
+def test_slicing(draeger_data1):
+    cutoff = 10
+    data: DraegerEITData = draeger_data1
+
+    assert data[cutoff] == data[cutoff]
+    assert data[0:cutoff] == data[:cutoff]
+    # assert data[cutoff : len(data)] == data[cutoff:]
+
+    # assert Sequence.merge(data[:cutoff], data[cutoff:]) == data
+    # assert len(data[:cutoff]) == cutoff
+
+    # assert len(data) == len(data[cutoff:]) + len(data[-cutoff:])
+    # assert len(data) == len(data[:cutoff]) + len(data[:-cutoff])