Update the command set in BOUT++functions.cmake to make ctest use pytest for integrated tests

(rather than running ``./runtest`)

* The specific python test filename (e.g., `test_foo.py`) is generated in `bout_add_integrated_test`.
* then passed to `bout_add_integrated_or_mms_test` via a new `PYTHON_TEST_FILE` argument.
* Modified `add_test()` to execute `pytest <filename>` for integrated tests (preserves the `./runtest` fallback for MMS tests).

Author: tomchapman

cmake/BOUT++functions.cmake

@@ -172,7 +172,7 @@ endfunction()
 #
 function(bout_add_integrated_or_mms_test BUILD_CHECK_TARGET TESTNAME)
   set(options USE_RUNTEST USE_DATA_BOUT_INP)
-  set(oneValueArgs EXECUTABLE_NAME PROCESSORS DOWNLOAD DOWNLOAD_NAME)
+  set(oneValueArgs EXECUTABLE_NAME PROCESSORS DOWNLOAD DOWNLOAD_NAME PYTHON_TEST_FILE)
   set(multiValueArgs SOURCES EXTRA_FILES REQUIRES CONFLICTS TESTARGS
                      EXTRA_DEPENDS
   )
@@ -252,9 +252,16 @@ function(bout_add_integrated_or_mms_test BUILD_CHECK_TARGET TESTNAME)
     set(BOUT_TEST_OPTIONS_PROCESSORS 1)
   endif()
 
-  # Set the actual test command
+# Set the actual test command
   if(BOUT_TEST_OPTIONS_USE_RUNTEST)
-    add_test(NAME ${TESTNAME} COMMAND ./runtest ${BOUT_TEST_OPTIONS_TESTARGS})
+    if(BOUT_TEST_OPTIONS_PYTHON_TEST_FILE)
+      # It's an integrated test with a specific python file
+      add_test(NAME ${TESTNAME} COMMAND pytest ${BOUT_TEST_OPTIONS_PYTHON_TEST_FILE} ${BOUT_TEST_OPTIONS_TESTARGS})
+    else()
+      # It's an MMS test still using the 'runtest' script
+      add_test(NAME ${TESTNAME} COMMAND ./runtest ${BOUT_TEST_OPTIONS_TESTARGS})
+    endif()
+
     set_tests_properties(
       ${TESTNAME} PROPERTIES ENVIRONMENT
                              PYTHONPATH=${BOUT_PYTHONPATH}:$ENV{PYTHONPATH}
@@ -287,17 +294,20 @@ endfunction()
 
 # Add a new integrated test. See `bout_add_integrated_or_mms_test` for arguments
 function(bout_add_integrated_test TESTNAME)
+  # Construct the Python test filename
+  string(REGEX REPLACE "^(test-)?(.+)$" "test_\\2.py" TEST_FILENAME "${TESTNAME}")
+  string(REPLACE "-" "_" TEST_FILENAME "${TEST_FILENAME}")
+  string(REPLACE "test_test_" "test_" TEST_FILENAME "${TEST_FILENAME}")
+
   bout_add_integrated_or_mms_test(
-    build-check-integrated-tests ${TESTNAME} ${ARGV}
+    build-check-integrated-tests ${TESTNAME} PYTHON_TEST_FILE ${TEST_FILENAME} ${ARGV}
   )
-  if(TARGET ${TESTNAME}) # Don't copy if the test has been skipped
-    string(REGEX REPLACE "^(test-)?(.+)$" "test_\\2.py" TEST_FILENAME "${TESTNAME}")
-    string(REPLACE "-" "_" TEST_FILENAME "${TEST_FILENAME}")
-    string(REPLACE "test_test_" "test_" TEST_FILENAME "${TEST_FILENAME}")
+
+  # 3. Only copy the file if the test wasn't skipped due to missing requirements
+  if(TARGET ${TESTNAME})
     bout_copy_file(${TEST_FILENAME})
   endif()
 endfunction()
-
 # Add a new MMS test. See `bout_add_integrated_or_mms_test` for arguments
 function(bout_add_mms_test TESTNAME)
   bout_add_integrated_or_mms_test(build-check-mms-tests ${TESTNAME} ${ARGV})