test(command_line_t): improve test robustness

This commit replaces the previously fragile unit tests for the
command_line_t type with tests that no longer require launching an
fpm subprocess via execute_command_line and checking that child
process's exit status.  The test main program also now prints
instructions for how to run the command_line_t tests if the flags
for running those tests is not detected.

test/command_line_test.F90

@@ -35,7 +35,7 @@ function results() result(test_results)
     test_descriptions = [ & 
       test_description_t(string_t("returning the value passed after a command-line flag"), check_flag_value), &
       test_description_t(string_t("returning an empty string when a flag value is missing"), handle_missing_flag_value), &
-      test_description_t(string_t("detecting a present command-line argument"), check_command_line_argument) &
+      test_description_t(string_t("detecting a present command-line argument"), check_argument_present) &
     ]   
 #else
     ! Work around missing Fortran 2008 feature: associating a procedure actual argument with a procedure pointer dummy argument:
@@ -57,38 +57,20 @@ function results() result(test_results)
 
   function check_flag_value() result(test_passes)
     logical test_passes
-    integer exit_status, command_status
-    character(len=132) command_message
-
-    call execute_command_line( &
-      command = "fpm run --example get-flag-value -- --input-file some_file_name", &
-      wait = .true., exitstat = exit_status, cmdstat = command_status, cmdmsg = command_message &
-    )   
-    test_passes = exit_status == 0 
+    type(command_line_t) command_line
+    test_passes = command_line%flag_value("--test") == "command_line_t"
   end function
 
   function handle_missing_flag_value() result(test_passes)
     logical test_passes
-    integer exit_status, command_status
-    character(len=132) command_message
-
-    call execute_command_line( &
-      command = "fpm run --example handle-missing-flag -- --empty-flag", &
-      wait = .true., exitstat = exit_status, cmdstat = command_status, cmdmsg = command_message &
-    )   
-    test_passes = exit_status == 0 
+    type(command_line_t) command_line
+    test_passes = command_line%flag_value("--type") == ""
   end function
 
-  function check_command_line_argument() result(test_passes)
+  function check_argument_present() result(test_passes)
     logical test_passes
-    integer exit_status, command_status
-    character(len=132) command_message
-
-    call execute_command_line( &
-      command = "fpm run --example check-command-line-argument -- --some-argument", &
-      wait = .true., exitstat = exit_status, cmdstat = command_status, cmdmsg = command_message &
-    )
-    test_passes = exit_status == 0
+    type(command_line_t) command_line
+    test_passes = command_line%argument_present(["--type"])
   end function
 
 end module command_line_test_m

test/main.F90

@@ -27,27 +27,38 @@ program main
   type(test_description_test_t) test_description_test
   type(vector_test_description_test_t) vector_test_description_test
 
+  type(command_line_t) command_line
+
   integer :: passes=0, tests=0
 
-  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
+  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
 
   call bin_test%report(passes, tests)
   call formats_test%report(passes, tests)
   call string_test%report(passes, tests)
   call test_result_test%report(passes, tests)
   call test_description_test%report(passes, tests)
   call vector_test_description_test%report(passes,tests)
-  if (.not. GitHub_CI())  call command_line_test%report(passes, tests)
+
+  if (.not. GitHub_CI())  then
+    if (command_line%argument_present(["--test"])) then
+      call command_line_test%report(passes, tests)
+    else
+      write(*,"(a)")  &
+      new_line("") // &
+      "To also test Julienne's command_line_t type, append the following to your fpm test command:" // &
+      new_line("") // &
+      "-- --test command_line_t --type"
+    end if
+  end if
 
 #if HAVE_MULTI_IMAGE_SUPPORT
   if (this_image()==1) then