force `subprocess.run` to check return code is 0

In general, this should help to capture unintentional errors.

Where the change has created failures, they have been fixed. (Mostly because the git repository that was looked for was missing.)

tests.py

@@ -11,6 +11,41 @@ import pytest
 mod = importlib.import_module("mpsd-software-environment")
 
 
+def create_mock_git_repository(target_directory, create_directory=True):
+    """
+    Create a git repository in the directory `target_directory`.
+
+    Arguments
+    ---------
+    target_directory : pathlib.Path
+      - path at which the root of the repository should be located (i.e. `.git` folder)
+
+    create_directory : bool
+      - create `target_directory` and parent directories if True
+
+    """
+    # create directory first
+    if create_directory:
+        target_directory.mkdir(parents=True)
+
+    # then create git repository:
+    with mod.os_chdir(str(target_directory)):
+        subprocess.run("git init .", shell=True, check=True)
+        subprocess.run("echo 'fake content' > readme.txt", shell=True, check=True)
+        subprocess.run("git add readme.txt", shell=True, check=True)
+        subprocess.run("pwd", shell=True)
+
+        # if email and username are not available (such as on naked test container),
+        # git may complain. We set a temporary user for this one commit to work around
+        # that.
+        user_details = "-c user.name='Tes Ta' -c user.email='tester@some-ci.org'"
+        subprocess.run(
+            f'git {user_details} commit -m "first commit" readme.txt',
+            shell=True,
+            check=True,
+        )
+
+
 def test_os_chdir(tmp_path):
     """Test the os_chdir context manager."""
     # create a temporary directory for testing
@@ -30,39 +65,47 @@ def test_os_chdir(tmp_path):
 
 def test_prepare_environment(tmp_path):
     """Simulate running preparation of environment.
-
+    
     Simulate running ./install-software-environment.py --release dev-23a \
       --target-directory /tmp/test_prepare_env
     prepare_env is run when cmd is not specified, we can test cmd='prepare'
     and cmd=None to check both cases
     """
-    script_dir = tmp_path / "test_prepare_env"
+    script_dir = tmp_path / "mpsd_opt" / "linux_debian_11"
     spack_environments = "spack-environments"
     mpsd_release_to_test = "dev-23a"
     release_base_dir = script_dir / mpsd_release_to_test
     # check that the test directory does not exist
     assert not script_dir.exists()
 
+    # prepare_environment expects to be executed in git repository
+    # (mpsd-software-environments). It queries the commit on which we are to
+    # log that information. For this to work, we need to execute the command
+    # within a directory tree that has a git repository at the same or high
+    # level. Let's create one:
+    create_mock_git_repository(script_dir)
+
+    # now call the function we want to test
     result = mod.prepare_environment(
-        mpsd_release=mpsd_release_to_test, script_dir=(script_dir)
+        mpsd_release=mpsd_release_to_test, script_dir=script_dir
     )
-    # wait for 20 seconds for the git clone to finish
-    # time.sleep(20)
+
     # check if the directory now is created
     assert release_base_dir.exists()
     # check for spack-environments directory
     assert spack_environments in os.listdir(release_base_dir)
-    # check if the git branch is correctly checked out
-    assert (
-        subprocess.run(
-            f"cd {str(release_base_dir/spack_environments)} && git branch",
-            shell=True,
-            capture_output=True,
-        )
-        .stdout.decode("utf-8")
-        .split("\n")[0]
-        == f"* {mpsd_release_to_test}"
+
+    # check if the git branch is correctly checked out. We expect output such as
+    # git_branch_stdout = '* dev-23a\n  develop\n'
+    # The entry with the '* ' prefix is the active branch.
+    git_branch_output_raw = subprocess.run(
+        f"cd {str(release_base_dir/spack_environments)} && git branch",
+        shell=True,
+        capture_output=True,
     )
+    git_branch_stdout = git_branch_output_raw.stdout.decode("utf-8")
+    assert f"* {mpsd_release_to_test}" in git_branch_stdout
+
     # check that result is a list and contains atleast ['global','foss2021a-mpi']
     assert isinstance(result, list)
     assert "global" in result
@@ -91,6 +134,7 @@ def test_setup_log_cmd(tmp_path):
         initial_bytes = 0
 
     # run the prepare_env functionality
+    create_mock_git_repository(target_directory=script_dir, create_directory=True)
     mod.prepare_environment(mpsd_release=mpsd_release_to_test, script_dir=(script_dir))
 
     # check that logs/install-software-environment.log is updated
@@ -103,20 +147,19 @@ def test_setup_log_cmd(tmp_path):
         assert "Spack environments branch: dev-23a " in last_line
 
 
-def test_install_environment(tmp_path):
-    """Test the installation of a toolchain.
-
-    This is a long test, its handy to test this with print statements printed to
-    stdout, use:
-      pytest -s
-    Expect an Exception when wrong toolchains are provided
-    """
+def test_install_environment_wrong_toolchain(tmp_path):
+    """Test exception is raised for non-existing toolchain."""
+    # Expect an Exception when wrong toolchains are provided
     with pytest.raises(Exception):
         mod.install_environment(
             mpsd_release="dev-23a",
             toolchains=["wrong-toolchain"],
             script_dir=(tmp_path),
         )
+
+
+def test_install_environment_wrong_mpsd_release(tmp_path):
+    """Test exception is raised for non-existing mpsd release."""
     # Expect an Exception when wrong mpsd_release is provided (part of
     # prepare_environment)
     with pytest.raises(Exception):
@@ -125,11 +168,18 @@ def test_install_environment(tmp_path):
             toolchains=["foss2021a-mpi"],
             script_dir=(tmp_path),
         )
-    # prepare a test of global generic with only zlib to test the installation
-    # prepare dev-23a release
-    # script_dir = tmp_path / "test_global_generic"
-    # for actaual installation avoid tmp_path as the lenght of the path is too long
-    # and spack complains
+
+
+def test_install_environment_zlib():
+    """Test installation of toolchain."""
+    # Prepare a test installation of global generic
+    # with only zlib to test the installation
+    # This is a long test,
+    # its handy to test this with print statements printed to
+    # stdout, use:
+    #   pytest -s
+    # for this installation avoid tmp_path as
+    # the length of the path becomes too long and spack complains
     script_dir = Path("/tmp/test_global_generic")
     if script_dir.exists():
         shutil.rmtree(script_dir)
@@ -138,6 +188,7 @@ def test_install_environment(tmp_path):
     toolchain_to_test = "global_generic"
     mpsd_microarch = os.getenv("MPSD_MICROARCH", "UNKNOWN_MICROARCH")
     release_base_dir = script_dir / mpsd_release_to_test
+    create_mock_git_repository(target_directory=script_dir, create_directory=False)
     mod.prepare_environment(mpsd_release=mpsd_release_to_test, script_dir=(script_dir))
     # Patch the spack environments to create a fake global_generic
     # create a test toolchain