Add a test checking for CONDA-installed binaries

src/brainreg/backend/niftyreg/niftyreg_binaries.py

@@ -16,7 +16,12 @@
 
 _IS_WINDOWS_OS = os_system_name == "Windows"
 
-def conda_install_path() -> Optional[Path]:
+packaged_binaries_folder = (
+    Path(__file__).parent.parent.parent / "bin" / "nifty_reg"
+)
+
+
+def conda_niftyreg_path() -> Optional[Path]:
     """
     If a conda install of niftyreg is available, return the directory
     containing the niftyreg binaries.
@@ -46,7 +51,7 @@ def conda_install_path() -> Optional[Path]:
     return None
 
 
-_CONDA_INSTALL_PATH = conda_install_path()
+_CONDA_NIFTYREG_BINARY_PATH = conda_niftyreg_path()
 
 
 def get_binary(program_name: str) -> Path:
@@ -56,17 +61,14 @@ def get_binary(program_name: str) -> Path:
     If niftyreg is installed via conda, use those binaries, otherwise fall
     back on bundled binaries.
     """
-    if _CONDA_INSTALL_PATH is not None:
-        bin_path = _CONDA_INSTALL_PATH / program_name
+    if _CONDA_NIFTYREG_BINARY_PATH is not None:
+        bin_path = _CONDA_NIFTYREG_BINARY_PATH / program_name
     else:
-        binaries_folder = (
-            Path(__file__).parent.parent.parent / "bin" / "nifty_reg"
-        )
-        bin_path = Path(binaries_folder) / os_folder_name / program_name
-
+        bin_path = packaged_binaries_folder / os_folder_name / program_name
+
     # Append exe label to Windows executables
     # It looks like subprocess is actually able to cope without the .exe appended,
     # but just to be safe we'll include it on Windows OS calls
     if _IS_WINDOWS_OS:
-        bin_path = bin_path.parent / f"{bin_path.name}.exe"
+        bin_path = bin_path.parent / f"{bin_path.stem}.exe"
     return bin_path

tests/tests/test_backend/test_niftyreg_detection.py

@@ -0,0 +1,68 @@
+import os
+from pathlib import Path
+from typing import Tuple
+
+import pytest
+
+from brainreg.backend.niftyreg.niftyreg_binaries import (
+    _CONDA_NIFTYREG_BINARY_PATH,
+    get_binary,
+)
+from brainreg.backend.niftyreg.niftyreg_binaries import (
+    packaged_binaries_folder,
+)
+
+
+def packaged_binaries_are_used() -> Tuple[bool, Path]:
+    """
+    Return a (bool, Path) tuple which has the values:
+        boolean:
+            TRUE if the get_binary function points to one of the niftyreg binaries
+             that are included with the package.
+            FALSE otherwise.
+        Path:
+            The path to the folder containing the niftyreg binaries that were found
+    """
+    using_binary = get_binary("reg_aladin")
+    return (
+        packaged_binaries_folder in using_binary.parents,
+        using_binary.parent,
+    )
+
+
+def test_conda_with_niftyreg():
+    """
+    Check the following:
+    - If we are not in a conda environment, the packaged niftyreg binaries are used by the backend
+    - If we are in a conda environment and niftyreg is not conda-installed, the packaged niftyreg binaries are used by the backend
+    - If we are in a conda environment and niftyreg IS conda-installed, the conda-installed binaries are used by the backend.
+    """
+    if "CONDA_PREFIX" not in os.environ:
+        # We are not in a conda envrionment
+        # _CONDA_NIFTYREG_BINARY_PATH should be none
+        assert (
+            _CONDA_NIFTYREG_BINARY_PATH is None
+        ), f"Not in a conda environment but _CONDA_NIFTYREG_BINARY_PATH is non-None: {_CONDA_NIFTYREG_BINARY_PATH}"
+
+        using_packaged_binaries, bin_folder = packaged_binaries_are_used()
+        assert (
+            using_packaged_binaries
+        ), f"There is no CONDA_PREFIX, but non-packaged binaries in {bin_folder} are being used!"
+    else:
+        # We are in a conda environment.
+        # Either this environment does not have niftyreg installed, or it does.
+        if _CONDA_NIFTYREG_BINARY_PATH is None:
+            # Apparently niftyreg is not installed in this environment
+            # Assert the located binaries are the packaged ones
+            using_packaged_binaries, bin_folder = packaged_binaries_are_used()
+            assert (
+                using_packaged_binaries
+            ), f"Conda environment without niftyreg installed exists, but non-packaged binaries in {bin_folder} are being used."
+        else:
+            # We are in a conda environment that _has_ niftyreg conda-installed
+            # Assert that we are using the CONDA-installed binaries
+            using_packaged_binaries, bin_folder = packaged_binaries_are_used()
+            assert (
+                not using_packaged_binaries,
+                f"Packaged binaries are being used despite appearing to be installed by CONDA at {_CONDA_NIFTYREG_BINARY_PATH}",
+            )