Have cli analysis tests explicitly set multithreading env variables t…

…o 1.

This commit adds an auto-used fixture for all analysis tests, that sets the environment variables for multithreading `OMP_NUM_THREADS`, `MKL_NUM_THREADS`, and `NUMEXPR_NUM_THREADS` all to 1. This can cause the issue of those tests hanging, as numpy uses all resources available if those env variables are not explicitly set.

tests/ert/ui_tests/cli/analysis/conftest.py

@@ -0,0 +1,28 @@
+import os
+import sys
+
+import pytest
+
+
+@pytest.fixture(autouse=True)
+def reduce_omp_num_threads_count():
+    if sys.platform != "darwin":
+        yield
+        return
+    multithreading_env_variables = [
+        ["OMP_NUM_THREADS", "1"],  # OpenMP
+        ["MKL_NUM_THREADS", "1"],  # Intel Math Kernel Library
+        ["NUMEXPR_NUM_THREADS", "1"],  # NumExpr library in Python
+    ]
+    for option in multithreading_env_variables:
+        env_var_name = option[0]
+        option[1], os.environ[env_var_name] = os.environ.get(env_var_name), option[1]
+
+    yield
+
+    for option in multithreading_env_variables:
+        env_var_name = option[0]
+        if option[1] is None:
+            del os.environ[env_var_name]
+        else:
+            os.environ[env_var_name] = option[1]