diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 2bbb436e6..e7e8ed257 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -189,7 +189,7 @@ jobs:
         dependency_cmake_options: |
           ecmwf-ifs/fiat: "-G Ninja -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} -DENABLE_TESTS=OFF -DENABLE_MPI=ON"
         cmake_options:    "-G Ninja -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} ${{ matrix.cmake_options }} -DENABLE_MPI=ON -DENABLE_FFTW=ON -DENABLE_ETRANS=ON"
-        ctest_options: "${{ matrix.ctest_options }}"
+        ctest_options: "${{ matrix.ctest_options }} -LE will_fail"
 
     - name: Verify tools
       run: |
diff --git a/cmake/ectrans_compile_options.cmake b/cmake/ectrans_compile_options.cmake
index e898c7296..16ddc0c78 100644
--- a/cmake/ectrans_compile_options.cmake
+++ b/cmake/ectrans_compile_options.cmake
@@ -6,6 +6,10 @@
 # granted to it by virtue of its status as an intergovernmental organisation
 # nor does it submit to any jurisdiction.
 
+# Flag to tell compiler that Fortran side has no program
+# Needed if linking a C executable against some Fortran objects with some compilers
+# Not needed for most
+set( NO_FORTRAN_MAIN_FLAG "" )
 
 if( CMAKE_Fortran_COMPILER_ID MATCHES "XL" )
   ecbuild_add_fortran_flags("-qextname -qnobindcextname")
@@ -21,6 +25,8 @@ elseif( CMAKE_Fortran_COMPILER_ID MATCHES "NVHPC" )
   ecbuild_add_fortran_flags("-traceback"      BUILD DEBUG )
   ecbuild_add_fortran_flags("-fast"           BUILD RELEASE )
   ecbuild_add_fortran_flags("-gopt -fast"     BUILD RELWITHDEBINFO )
+
+  set( NO_FORTRAN_MAIN_FLAG "-Mnomain")
 elseif( CMAKE_Fortran_COMPILER_ID MATCHES "Cray" )
   ecbuild_add_fortran_flags("-hnomessage=878")  # A module named ... has already been directly or indirectly use associated into this scope
   ecbuild_add_fortran_flags("-hnomessage=867")  # Module ... has no public objects declared in the module, therefore nothing can be use associated from the module.
@@ -31,6 +37,7 @@ elseif( CMAKE_Fortran_COMPILER_ID MATCHES "IntelLLVM" )
 elseif( CMAKE_Fortran_COMPILER_ID MATCHES "Intel" )
   ecbuild_add_fortran_flags("-march=core-avx2 -no-fma" BUILD BIT)
   ecbuild_add_fortran_flags("-fast-transcendentals -fp-model precise -fp-speculation=safe")
+  set( NO_FORTRAN_MAIN_FLAG "-nofor-main")
 endif()
 
 if( NOT DEFINED ECTRANS_HAVE_CONTIGUOUS_ISSUE )
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index bdbb32408..29e5ae163 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -6,6 +6,27 @@
 # granted to it by virtue of its status as an intergovernmental organisation
 # nor does it submit to any jurisdiction.
 
+# --------------------------------------------------------------------------------------------------
+# First establish which precisions to test
+# --------------------------------------------------------------------------------------------------
+
+set( precisions "" )
+if( HAVE_DOUBLE_PRECISION )
+  list( APPEND precisions "dp" )
+endif()
+if( HAVE_SINGLE_PRECISION )
+  list( APPEND precisions "sp" )
+endif()
+
+# --------------------------------------------------------------------------------------------------
+# Then set the MPI testing configuration
+# --------------------------------------------------------------------------------------------------
+
+set( ntasks 0 )
+if( HAVE_MPI )
+  list( APPEND ntasks 1 2 )
+endif()
+
 # --------------------------------------------------------------------------------------------------
 # Add a test for installation of ecTrans
 # --------------------------------------------------------------------------------------------------
@@ -37,25 +58,10 @@ add_test( NAME ectrans_test_install
           COMMAND ${CMAKE_CURRENT_BINARY_DIR}/test-install.sh ${_test_args} )
 
 # --------------------------------------------------------------------------------------------------
-# Add a test for SETUP_TRANS0
+# Add API tests
 # --------------------------------------------------------------------------------------------------
 
-ecbuild_add_executable(
-  TARGET  ectrans_test_setup_trans0
-  SOURCES trans/test_setup_trans0.F90
-  LIBS    ectrans_common
-  LINKER_LANGUAGE Fortran
-  NOINSTALL)
-set( ntasks 0 )
-if( HAVE_MPI )
-  list( APPEND ntasks 1 2 )
-endif()
-foreach( mpi ${ntasks} )
-    ecbuild_add_test( TARGET ectrans_test_setup_trans0_mpi${mpi}
-        COMMAND ectrans_test_setup_trans0
-        MPI ${mpi}
-    )
-endforeach()
+add_subdirectory( trans/api )
 
 # --------------------------------------------------------------------------------------------------
 # Add a test for tangent-linear/adjoint correspondence of INV_TRANS and DIR_TRANS combined (CPU
@@ -63,19 +69,6 @@ endforeach()
 # --------------------------------------------------------------------------------------------------
 
 if( HAVE_CPU )
-  set( precisions "" )
-  if( HAVE_DOUBLE_PRECISION )
-    list( APPEND precisions "dp" )
-  endif()
-  if( HAVE_SINGLE_PRECISION )
-    list( APPEND precisions "sp" )
-  endif()
-
-  set( ntasks 0 )
-  if( HAVE_MPI )
-    list( APPEND ntasks 1 2 )
-  endif()
-
   foreach( precision ${precisions} )
     foreach( mpi ${ntasks} )
       set( test_name ectrans_test_adjoint_mpi${mpi}_${precision} )
@@ -121,11 +114,6 @@ foreach( platform ${platforms} )
     set( parkind parkind_sp )
   endif()
 
-  set( ntasks 0 )
-  if( HAVE_MPI )
-    list( APPEND ntasks 1 2 )
-  endif()
-
   foreach( mpi ${ntasks} )
     ecbuild_add_test(TARGET ectrans_test_dirtrans_adjoint_${platform}_mpi${mpi}
       SOURCES trans/test_dirtrans_adjoint.F90
@@ -160,19 +148,6 @@ endforeach() # platform
 # --------------------------------------------------------------------------------------------------
 
 if( HAVE_CPU )
-  set( precisions "" )
-  if( HAVE_DOUBLE_PRECISION )
-    list( APPEND precisions "dp" )
-  endif()
-  if( HAVE_SINGLE_PRECISION )
-    list( APPEND precisions "sp" )
-  endif()
-
-  set( ntasks 0 )
-  if( HAVE_MPI )
-    list( APPEND ntasks 1 2 )
-  endif()
-
   foreach( precision ${precisions} )
     foreach( mpi ${ntasks} )
       set( test_name ectrans_test_gpnorm_trans_adjoint_mpi${mpi}_${precision} )
@@ -337,11 +312,7 @@ if( HAVE_ETRANS )
 
   foreach( prec dp sp )
     if( TARGET ectrans-lam-benchmark-cpu-${prec} )
-      set( ntasks 0 )
       set( nthreads 1 )
-      if( HAVE_MPI )
-        list( APPEND ntasks 1 2 )
-      endif()
       if( HAVE_OMP )
         list( APPEND nthreads 8 )
       endif()
diff --git a/tests/trans/api/CMakeLists.txt b/tests/trans/api/CMakeLists.txt
new file mode 100644
index 000000000..98db7d3de
--- /dev/null
+++ b/tests/trans/api/CMakeLists.txt
@@ -0,0 +1,73 @@
+# (C) Copyright 2025- ECMWF.
+#
+# This software is licensed under the terms of the Apache Licence Version 2.0
+# which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+# In applying this licence, ECMWF does not waive the privileges and immunities
+# granted to it by virtue of its status as an intergovernmental organisation
+# nor does it submit to any jurisdiction.
+
+# SETUP_TRANS0 contains no precision-specific code, so for that one we don't generate single- and
+# double-precision versions
+
+# Function for generating a suite of API tests for one external subroutine using CMake's
+# create_test_sourcelist function
+function( generate_api_test_suite )
+  set( options )
+  set( oneValueArgs SUITE_NAME)
+  set( multiValueArgs TEST_LIST WILL_FAIL_LIST )
+  cmake_parse_arguments( _PAR "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN} )
+  set( suite_name ${_PAR_SUITE_NAME} )
+  set( test_list ${_PAR_TEST_LIST} )
+  set( will_fail_list ${_PAR_WILL_FAIL_LIST} )
+
+  if( suite_name STREQUAL setup_trans0_test_suite )
+    set( precisions_to_test _ )
+  else()
+    set( precisions_to_test ${precisions} )
+  endif()
+
+  # Add API tests for this suite, with a separate driver executable for each precision
+  foreach( precision ${precisions_to_test} )
+    if( suite_name STREQUAL setup_trans0_test_suite )
+      set( libs ectrans_common )
+      set( prec_suffix "" )
+    else()
+      set( libs trans_${precision} )
+      set( prec_suffix "_${precision}" )
+    endif()
+
+    # Create test suite driver executable encapsulating all tests for this suite at this precision
+    create_test_sourcelist( _ ${suite_name}${prec_suffix}.c ${test_list} )
+    ecbuild_add_executable( TARGET ${suite_name}${prec_suffix}
+                            SOURCES
+                                ${suite_name}${prec_suffix}.c
+                                ${suite_name}.F90
+                                ${CMAKE_SOURCE_DIR}/tests/trans/api/util.F90
+                            LIBS ${libs} )
+
+    # Prevent the Fortran runtime from trying to provide a main program
+    target_link_options( ${suite_name}${prec_suffix} PRIVATE ${NO_FORTRAN_MAIN_FLAG} )
+
+    ectrans_target_fortran_module_directory( TARGET ${suite_name}${prec_suffix}
+        MODULE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/module/${suite_name}${prec_suffix} )
+
+    # Add a test for each MPI configuration
+    foreach( mpi ${ntasks} )
+      # Add each test in the test list for this precision and MPI configuration
+      foreach( test ${test_list} )
+        ecbuild_add_test( TARGET ${test}${prec_suffix}_mpi${mpi}
+                          COMMAND ${suite_name}${prec_suffix}
+                          ARGS ${test}
+                          MPI ${mpi} )
+
+        # Declare that this test should fail
+        if( ${test} IN_LIST will_fail_list )
+          set_property( TEST ${test}${prec_suffix}_mpi${mpi} PROPERTY WILL_FAIL TRUE )
+          set_property( TEST ${test}${prec_suffix}_mpi${mpi} PROPERTY LABELS "will_fail" )
+        endif()
+      endforeach()
+    endforeach()
+  endforeach()
+endfunction( generate_api_test_suite )
+
+add_subdirectory( setup_trans0 )
diff --git a/tests/trans/api/setup_trans0/CMakeLists.txt b/tests/trans/api/setup_trans0/CMakeLists.txt
new file mode 100644
index 000000000..30816c0cf
--- /dev/null
+++ b/tests/trans/api/setup_trans0/CMakeLists.txt
@@ -0,0 +1,23 @@
+# (C) Copyright 2025- ECMWF.
+#
+# This software is licensed under the terms of the Apache Licence Version 2.0
+# which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+# In applying this licence, ECMWF does not waive the privileges and immunities
+# granted to it by virtue of its status as an intergovernmental organisation
+# nor does it submit to any jurisdiction.
+
+# API tests for SETUP_TRANS0
+
+# Define list of SETUP_TRANS0 tests
+set( test_list
+  api_test_setup_trans0_eq_regions
+)
+
+# Define additional list setting tests that WILL_FAIL
+set( will_fail_list
+  "" # None yet
+)
+
+generate_api_test_suite( SUITE_NAME setup_trans0_test_suite
+                         TEST_LIST ${test_list}
+                         WILL_FAIL_LIST ${will_fail_list} )
diff --git a/tests/trans/api/setup_trans0/setup_trans0_test_suite.F90 b/tests/trans/api/setup_trans0/setup_trans0_test_suite.F90
new file mode 100644
index 000000000..7b0bef5c3
--- /dev/null
+++ b/tests/trans/api/setup_trans0/setup_trans0_test_suite.F90
@@ -0,0 +1,55 @@
+! (C) Copyright 2025- ECMWF.
+!
+! This software is licensed under the terms of the Apache Licence Version 2.0
+! which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+! In applying this licence, ECMWF does not waive the privileges and immunities
+! granted to it by virtue of its status as an intergovernmental organisation
+! nor does it submit to any jurisdiction.
+
+MODULE SETUP_TRANS0_TEST_SUITE
+
+IMPLICIT NONE
+
+#include "setup_trans0.h"
+
+CONTAINS
+
+!---------------------------------------------------------------------------------------------------
+
+! NOTE: SETUP_TRANS0 hardly has any error-prone code - it mostly just sets module variables
+! Hence, the only logic we test here is the equal regions initialisation
+! For the real tests of initialisation, check the suite for SETUP_TRANS
+
+!---------------------------------------------------------------------------------------------------
+
+! Test SETUP_TRANS0 with equal regions enabled
+INTEGER FUNCTION API_TEST_SETUP_TRANS0_EQ_REGIONS() RESULT(RET) BIND(C)
+  USE UTIL, ONLY: DETECT_MPIRUN
+  USE MPL_MODULE, ONLY: MPL_INIT, MPL_NPROC, MPL_END
+  USE EC_PARKIND, ONLY: JPIM
+
+  LOGICAL :: LUSE_MPI
+  INTEGER(KIND=JPIM) :: NPROC
+
+  LUSE_MPI = DETECT_MPIRUN()
+
+  IF (LUSE_MPI) THEN
+    CALL MPL_INIT
+    NPROC = MPL_NPROC()
+  ELSE
+    NPROC = 1
+  ENDIF
+
+  CALL SETUP_TRANS0(LDMPOFF=.NOT. LUSE_MPI, LDEQ_REGIONS=.TRUE., KPRGPNS=NPROC, KPRGPEW=1, &
+    &               KPRTRW=NPROC)
+
+  IF (LUSE_MPI) THEN
+    CALL MPL_END(LDMEMINFO=.FALSE.)
+  ENDIF
+
+  RET = 0
+END FUNCTION API_TEST_SETUP_TRANS0_EQ_REGIONS
+
+!---------------------------------------------------------------------------------------------------
+
+END MODULE SETUP_TRANS0_TEST_SUITE
diff --git a/tests/trans/api/util.F90 b/tests/trans/api/util.F90
new file mode 100644
index 000000000..57e1d4f11
--- /dev/null
+++ b/tests/trans/api/util.F90
@@ -0,0 +1,52 @@
+! (C) Copyright 2025- ECMWF.
+!
+! This software is licensed under the terms of the Apache Licence Version 2.0
+! which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
+! In applying this licence, ECMWF does not waive the privileges and immunities
+! granted to it by virtue of its status as an intergovernmental organisation
+! nor does it submit to any jurisdiction.
+
+MODULE UTIL
+
+IMPLICIT NONE
+
+PRIVATE
+PUBLIC :: DETECT_MPIRUN
+
+CONTAINS
+
+LOGICAL FUNCTION DETECT_MPIRUN()
+  USE EC_ENV_MOD, ONLY : EC_PUTENV
+
+  INTEGER :: ILEN
+  CHARACTER(LEN=32), DIMENSION(4) :: CMPIRUN_DETECT
+  CHARACTER(LEN=4) :: CLENV
+  INTEGER :: IVAR
+
+  ! Environment variables that are set when mpirun, srun, aprun, ... are used
+  CMPIRUN_DETECT(1) = 'OMPI_COMM_WORLD_SIZE'  ! OPENMPI
+  CMPIRUN_DETECT(2) = 'ALPS_APP_PE'           ! CRAY PE
+  CMPIRUN_DETECT(3) = 'PMI_SIZE'              ! INTEL
+  CMPIRUN_DETECT(4) = 'SLURM_NTASKS'          ! SLURM
+
+  DETECT_MPIRUN = .FALSE.
+  DO IVAR = 1, 4
+    CALL GET_ENVIRONMENT_VARIABLE(NAME=TRIM(CMPIRUN_DETECT(IVAR)), LENGTH=ILEN)
+    IF (ILEN > 0) THEN
+      DETECT_MPIRUN = .TRUE.
+      EXIT ! Break
+    ENDIF
+  ENDDO
+
+  CALL GET_ENVIRONMENT_VARIABLE(NAME="ECTRANS_USE_MPI", VALUE=CLENV, LENGTH=ILEN )
+  IF (ILEN > 0) THEN
+    DETECT_MPIRUN = .TRUE.
+    IF (TRIM(CLENV) == "0" .OR. TRIM(CLENV) == "OFF" .OR. TRIM(CLENV) == "OFF" &
+      & .OR. TRIM(CLENV) == "F") THEN
+      DETECT_MPIRUN = .FALSE.
+    ENDIF
+    CALL EC_PUTENV("DR_HOOK_ASSERT_MPI_INITIALIZED=0", OVERWRITE=.TRUE.)
+  ENDIF
+END FUNCTION
+
+END MODULE UTIL
\ No newline at end of file
diff --git a/tests/trans/test_setup_trans0.F90 b/tests/trans/test_setup_trans0.F90
deleted file mode 100644
index 951976bde..000000000
--- a/tests/trans/test_setup_trans0.F90
+++ /dev/null
@@ -1,108 +0,0 @@
-! (C) Copyright 2005- ECMWF.
-! 
-! This software is licensed under the terms of the Apache Licence Version 2.0
-! which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
-! In applying this licence, ECMWF does not waive the privileges and immunities
-! granted to it by virtue of its status as an intergovernmental organisation
-! nor does it submit to any jurisdiction.
-!
-
-PROGRAM TEST_SETUP_TRANS0
-USE EC_PARKIND  ,ONLY : JPIM
-USE MPL_MODULE  ,ONLY : MPL_INIT, MPL_END, MPL_BARRIER, MPL_MYRANK, MPL_NPROC
-USE ABORT_TRANS_MOD, ONLY : ABORT_TRANS
-USE YOMHOOK, ONLY : JPHOOK, DR_HOOK
-
-IMPLICIT NONE
-
-INTEGER(KIND=JPIM) :: NPROC,NPRGPNS,NPRGPEW,NPRTRW,NPRTRV
-INTEGER(KIND=JPIM) :: NOUT, MYPROC
-REAL(KIND=JPHOOK)  :: ZHOOK_HANDLE
-CHARACTER(LEN=6) :: CLNAME
-LOGICAL :: LUSE_MPI
-
-#include "setup_trans0.h"
-
-LUSE_MPI = detect_mpirun()
-
-IF(LUSE_MPI) THEN
-  CALL MPL_INIT
-  MYPROC = MPL_MYRANK()
-  NPROC = MPL_NPROC()
-  NOUT = 20
-  WRITE(CLNAME,'(A,I2.2)') 'OUT.',MYPROC
-  OPEN(NOUT,FILE=CLNAME)
-ELSE
-  NOUT   = 6
-  MYPROC = 1
-  NPROC  = 1
-ENDIF
-
-CALL DR_HOOK('PROGRAM', 0, ZHOOK_HANDLE)
-
-! ======================================================================================
-! NPROC must match NPRGPNS * NPRGPEW
-NPRTRV  = 1
-NPRTRW  = NPROC / NPRTRV
-NPRGPEW = 1
-NPRGPNS = NPROC
-! ======================================================================================
-
-IF (MYPROC == 1) WRITE(NOUT,*) ' LUSE_MPI= ',LUSE_MPI
-
-IF(NPROC /= NPRTRW*NPRTRV) THEN
-  PRINT *,'NPRGPNS,NPRGPEW,NPRTRW,NPRTRV ',NPRGPNS,NPRGPEW,NPRTRW,NPRTRV
-  CALL ABORT_TRANS('NPRGPNS*NPRGPEW /= NPRTRW*NPRTRV')
-ENDIF
-
-CALL SETUP_TRANS0(KOUT=NOUT,KERR=0,KPRINTLEV=2, &
- & KMAX_RESOL=1,&
- & LDEQ_REGIONS=.TRUE., &
- & KPRGPNS=NPRGPNS, KPRGPEW=NPRGPEW, KPRTRW=NPRTRW,&
- & LDMPOFF=.NOT.LUSE_MPI)
-
-CALL DR_HOOK('PROGRAM', 1, ZHOOK_HANDLE)
-
-IF(LUSE_MPI) THEN
- CALL MPL_BARRIER()
- CALL MPL_END
-ENDIF
-
-CONTAINS
-
-function detect_mpirun() result(lmpi_required)
-  use ec_env_mod, only : ec_putenv
-  logical :: lmpi_required
-  integer :: ilen
-  integer, parameter :: nvars = 4
-  character(len=32), dimension(nvars) :: cmpirun_detect
-  character(len=4) :: clenv
-  integer :: ivar
-
-  ! Environment variables that are set when mpirun, srun, aprun, ... are used
-  cmpirun_detect(1) = 'OMPI_COMM_WORLD_SIZE'  ! openmpi
-  cmpirun_detect(2) = 'ALPS_APP_PE'           ! cray pe
-  cmpirun_detect(3) = 'PMI_SIZE'              ! intel
-  cmpirun_detect(4) = 'SLURM_NTASKS'          ! slurm
-
-  lmpi_required = .false.
-  do ivar = 1, nvars
-    call get_environment_variable(name=trim(cmpirun_detect(ivar)), length=ilen)
-    if (ilen > 0) then
-      lmpi_required = .true.
-      exit ! break
-    endif
-  enddo
-
-  call get_environment_variable(name="ECTRANS_USE_MPI", value=clenv, length=ilen )
-  if (ilen > 0) then
-      lmpi_required = .true.
-      if( trim(clenv) == "0" .or. trim(clenv) == "OFF" .or. trim(CLENV) == "off" .or. trim(clenv) == "F" ) then
-        lmpi_required = .false.
-      endif
-      call ec_putenv("DR_HOOK_ASSERT_MPI_INITIALIZED=0", overwrite=.true.)
-  endif
-end function
-
-
-END PROGRAM