add unit tests for anat pipeline (might change to more general later...)

test/unittests/pipelines/t1_linear/test_anat_linear_pipeline.py

@@ -0,0 +1,68 @@
+import re
+
+import pytest
+
+
+def test_anat_linear_pipeline_no_input_error(tmp_path):
+    from clinica.pipelines.t1_linear.anat_linear_pipeline import AnatLinear
+
+    with pytest.raises(
+        RuntimeError,
+        match=(
+            "The AnatLinear pipeline does not contain BIDS "
+            "nor CAPS directory at the initialization."
+        ),
+    ):
+        AnatLinear()
+
+
+def test_anat_linear_pipeline_single_bids_input_error(tmp_path):
+    from clinica.pipelines.t1_linear.anat_linear_pipeline import AnatLinear
+    from clinica.utils.exceptions import ClinicaBIDSError
+
+    with pytest.raises(
+        ClinicaBIDSError,
+        match=re.escape(
+            f"The BIDS directory ({tmp_path}) you provided "
+            "is missing a dataset_description.json file."
+        ),
+    ):
+        AnatLinear(bids_directory=str(tmp_path))
+
+
+def test_anat_linear_pipeline_single_caps_input_error(tmp_path):
+    from clinica.pipelines.t1_linear.anat_linear_pipeline import AnatLinear
+    from clinica.utils.exceptions import ClinicaCAPSError
+
+    with pytest.raises(
+        ClinicaCAPSError,
+        match=re.escape(
+            f"The CAPS directory ({tmp_path}) you provided "
+            "is missing a dataset_description.json file."
+        ),
+    ):
+        AnatLinear(caps_directory=str(tmp_path))
+
+
+def test_anat_linear_pipeline_write_caps_dataset_description(tmp_path):
+    from clinica.pipelines.t1_linear.anat_linear_pipeline import AnatLinear
+    from clinica.utils.caps import CAPSDatasetDescription, DatasetType
+
+    bids = tmp_path / "bids"
+    caps = tmp_path / "caps"
+    bids.mkdir()
+    caps.mkdir()
+    (bids / "dataset_description.json").touch()
+    (bids / "sub-01").mkdir()
+
+    AnatLinear(bids_directory=str(bids), caps_directory=str(caps))
+
+    files = [f for f in caps.iterdir()]
+    assert len(files) == 1
+
+    desc = CAPSDatasetDescription.from_file(caps / "dataset_description.json")
+
+    assert desc.name == "AnatLinear"
+    assert desc.bids_version == "1.7.0"
+    assert desc.caps_version == "1.0.0"
+    assert desc.dataset_type == DatasetType.DERIVATIVE