Skip llvm tests if llvmlite is not installed

conftest.py

@@ -51,6 +51,7 @@ try:
     import llvmlite
 except ImportError:
     collect_ignore += [os.path.join(SCRIPT_FOLDER, 'pystencils_tests/backends/llvm.py')]
+    collect_ignore += [os.path.join(SCRIPT_FOLDER, 'pystencils_tests/test_basic_usage_llvm.ipynb')]
     add_path_to_ignore('pystencils/llvm')
 
 try:

pystencils_tests/test_jacobi_llvm.py

-import numpy as np
+
 import pytest
+try:
+    from pystencils.llvm.llvmjit import generate_and_jit
+    from pystencils.llvm import create_kernel, make_python_function
+    from pystencils.cpu.cpujit import get_llc_command
+    from pystencils import Assignment, Field, show_code
+    import numpy as np
+except ModuleNotFoundError:
+    pytest.importorskip("llvmlite")
 
-from pystencils import Assignment, Field, show_code
-from pystencils.cpu.cpujit import get_llc_command
-from pystencils.llvm import create_kernel, make_python_function
-from pystencils.llvm.llvmjit import generate_and_jit
 
 
 def test_jacobi_fixed_field_size():

pystencils_tests/test_size_and_layout_checks_llvm.py

 import numpy as np
+import pytest
 
 from pystencils import Assignment, Field
-from pystencils.llvm import create_kernel, make_python_function
+try:
+    from pystencils.llvm import create_kernel, make_python_function
+except ModuleNotFoundError:
+    pytest.importorskip("llvmlite")
 
 
 def test_size_check():

pystencils_tests/test_sliced_iteration.py

@@ -30,6 +30,8 @@ def test_sliced_iteration():
 
 
 def test_sliced_iteration_llvm():
+    import pytest
+    pytest.importorskip("llvmlite")
     size = (4, 4)
     src_arr = np.ones(size)
     dst_arr = np.zeros_like(src_arr)