diff --git a/demo/test/main.F90 b/demo/test/main.F90
index 43792108..14265742 100644
--- a/demo/test/main.F90
+++ b/demo/test/main.F90
@@ -5,21 +5,33 @@
 
 program main
   use netCDF_file_test_m, only : netCDF_file_test_t
+  use iso_fortran_env, only : int64, real64
+  use julienne_m, only : command_line_t
   implicit none
 
-  real t_start, t_finish
-
+  integer(int64) t_start, t_finish, clock_rate
+  type(netCDF_file_test_t) netCDF_file_test
   integer :: passes=0, tests=0
 
-  call cpu_time(t_start)
-  block 
-    type(netCDF_file_test_t) netCDF_file_test
-    call netCDF_file_test%report(passes, tests)
-  end block
-  call cpu_time(t_finish)
+  print_usage_if_help_requested: &
+  block
+    type(command_line_t) command_line
+    character(len=*), parameter :: usage = &
+      new_line('') // new_line('') // &
+      'Usage: fpm test -- [--help] | [--contains <substring>]' // &
+      new_line('') // new_line('') // &
+      'where square brackets ([]) denote optional arguments, a pipe (|) separates alternative arguments,' // new_line('') // &
+      'angular brackets (<>) denote a user-provided value, and passing a substring limits execution to' // new_line('') // &
+      'the tests with test subjects or test descriptions containing the user-specified substring.' // new_line('')
+    if (command_line%argument_present([character(len=len("--help"))::"--help","-h"])) stop usage
+  end block print_usage_if_help_requested
+
+  call system_clock(t_start, clock_rate)
+  call netCDF_file_test%report(passes, tests)
+  call system_clock(t_finish)
 
   print *
-  print *,"Test suite execution time: ",t_finish - t_start
+  print *,"Test suite execution time: ", real(t_finish - t_start, real64)/real(clock_rate, real64)
   print *
   print '(*(a,:,g0))',"_________ In total, ",passes," of ",tests, " tests pass. _________"
 #if defined(MULTI_IMAGE_SUPPORT)
diff --git a/demo/test/netCDF_file_test_m.F90 b/demo/test/netCDF_file_test_m.F90
index db6555f8..9eddc165 100644
--- a/demo/test/netCDF_file_test_m.F90
+++ b/demo/test/netCDF_file_test_m.F90
@@ -8,7 +8,7 @@ module NetCDF_file_test_m
 
   ! External dependencies
   use assert_m
-  use julienne_m, only : string_t, test_t, test_result_t
+  use julienne_m, only : test_t, test_result_t, test_description_t, test_description_substring, string_t
   use netcdf, only : &
      nf90_create, nf90_def_dim, nf90_def_var, nf90_enddef, nf90_put_var, nf90_inquire_dimension, & ! functions
      nf90_close, nf90_open, nf90_inq_varid, nf90_get_var, nf90_inquire_variable, &
@@ -41,24 +41,22 @@ pure function subject() result(specimen)
 
   function results() result(test_results)
     type(test_result_t), allocatable :: test_results(:)
+    type(test_description_t), allocatable :: test_descriptions(:)
 
     character(len=*), parameter :: longest_description = &
           "writing and then reading gives input matching the output for a 1D double precision array"
 
+    test_descriptions = &
+      [ test_description_t("writing and then reading gives input matching the output for a 2D integer array", write_then_read_2D_integer), &
+        test_description_t("writing and then reading gives input matching the output for a 1D double precision array", write_then_read_1D_double) &
+      ]
     associate( &
-      descriptions => &
-        [ character(len=len(longest_description)) :: &
-          "writing and then reading gives input matching the output for a 2D integer array", &
-          "writing and then reading gives input matching the output for a 1D double precision array" &
-        ], &
-      outcomes => &
-        [ write_then_read_2D_integer(), & 
-          write_then_read_1D_double() &
-        ] & 
+      substring_in_subject => index(subject(), test_description_substring) /= 0, &
+      substring_in_description => test_descriptions%contains_text(string_t(test_description_substring)) &
     )
-      call_assert(size(descriptions) == size(outcomes))
-      test_results = test_result_t(descriptions, outcomes)
+      test_descriptions = pack(test_descriptions, substring_in_subject .or. substring_in_description)
     end associate
+    test_results = test_descriptions%run()
        
   end function
 
@@ -118,7 +116,7 @@ subroutine output_1D_double(file_name, data_out)
   end subroutine
 
   function write_then_read_2D_integer() result(test_passes)
-    logical, allocatable :: test_passes(:)
+    logical test_passes
     integer i, j
     integer, parameter :: ny = 12,  nx = 6
     integer, parameter :: data_written(*,*) = reshape([((i*j, i=1,nx), j=1,ny)], [ny,nx])
@@ -131,12 +129,12 @@ function write_then_read_2D_integer() result(test_passes)
       call NetCDF_file%input("data", data_read)
     end associate
 
-    test_passes = [all(data_written == data_read)]
+    test_passes = all(data_written == data_read)
 
   end function
 
   function write_then_read_1D_double() result(test_passes)
-    logical, allocatable :: test_passes(:)
+    logical test_passes
     integer i
     integer, parameter :: nx = 6
     double precision, parameter :: data_written(*) = dble([(i, i=1,nx)]), tolerance = 1.E-15
@@ -149,7 +147,7 @@ function write_then_read_1D_double() result(test_passes)
       call NetCDF_file%input("data", data_read)
     end associate
 
-    test_passes = [all(abs(data_written - data_read)<tolerance)]
+    test_passes = all(abs(data_written - data_read)<tolerance)
 
   end function