+our @EXPORT = qw<
+ plan
+ skip
+ done_testing
+ pass
+ fail
+ ok
+ is
+ isnt
+ like
+ unlike
+ cmp_ok
+ is_deeply
+ diag
+ note
+ BAIL_OUT
+>;
+
+=head1 ENVIRONMENT
+
+=head2 C<PERL_TEST_LEANER_USES_TEST_MORE>
+
+If this environment variable is set, L<Test::Leaner> will replace its functions by those from L<Test::More>.
+Moreover, the symbols that are imported when you C<use Test::Leaner> will be those from L<Test::More>, but you can still only import the symbols originally defined in L<Test::Leaner> (hence the functions from L<Test::More> that are not implemented in L<Test::Leaner> will not be imported).
+If your version of L<Test::More> is too old and doesn't have some symbols (like L</note> or L</done_testing>), they will be replaced in L<Test::Leaner> by croaking stubs.
+
+This may be useful if your L<Test::Leaner>-based test script fails and you want extra diagnostics.
+
+=cut
+
+sub _handle_import_args {
+ my @imports;
+
+ my $i = 0;
+ while ($i <= $#_) {
+ my $item = $_[$i];
+ my $splice;
+ if (defined $item) {
+ if ($item eq 'import') {
+ push @imports, @{ $_[$i+1] };
+ $splice = 2;
+ } elsif ($item eq 'no_diag') {
+ lock $plan if THREADSAFE;
+ $no_diag = 1;
+ $splice = 1;
+ }
+ }
+ if ($splice) {
+ splice @_, $i, $splice;
+ } else {
+ ++$i;
+ }
+ }
+
+ return @imports;
+}
+
+if ($ENV{PERL_TEST_LEANER_USES_TEST_MORE}) {
+ require Test::More;
+
+ my $leaner_stash = \%Test::Leaner::;
+ my $more_stash = \%Test::More::;
+
+ my %stubbed;
+
+ for (@EXPORT) {
+ my $replacement = exists $more_stash->{$_} ? *{$more_stash->{$_}}{CODE}
+ : undef;
+ unless (defined $replacement) {
+ $stubbed{$_}++;
+ $replacement = sub {
+ @_ = ("$_ is not implemented in this version of Test::More");
+ goto &croak;
+ };
+ }
+ no warnings 'redefine';
+ $leaner_stash->{$_} = $replacement;
+ }
+
+ my $import = sub {
+ my $class = shift;
+
+ my @imports = &_handle_import_args;
+ if (@imports == grep /^!/, @imports) {
+ # All imports are negated, or @imports is empty
+ my %negated;
+ /^!(.*)/ and ++$negated{$1} for @imports;
+ push @imports, grep !$negated{$_}, @EXPORT;
+ }
+
+ my @test_more_imports;
+ for (@imports) {
+ if ($stubbed{$_}) {
+ my $pkg = caller;
+ no strict 'refs';
+ *{$pkg."::$_"} = $leaner_stash->{$_};
+ } elsif (/^!/ or !exists $more_stash->{$_} or exists $leaner_stash->{$_}) {
+ push @test_more_imports, $_;
+ } else {
+ # Croak for symbols in Test::More but not in Test::Leaner
+ Exporter::import($class, $_);
+ }
+ }
+
+ my $test_more_import = 'Test::More'->can('import');
+ return unless $test_more_import;
+
+ @_ = (
+ 'Test::More',
+ @_,
+ import => \@test_more_imports,
+ );
+ {
+ lock $plan if THREADSAFE;
+ push @_, 'no_diag' if $no_diag;
+ }
+
+ goto $test_more_import;
+ };
+
+ no warnings 'redefine';
+ *import = $import;
+
+ return 1;
+}
+