Solution to task 2

1 files changed, 156 insertions, 0 deletions

diff --git a/challenge-203/jo-37/perl/ch-2.pl b/challenge-203/jo-37/perl/ch-2.pl
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+#!/usr/bin/perl -s
+
+use v5.18;
+use Test2::V0;
+
+use File::Find;
+use autodie;
+use experimental qw(signatures lexical_subs);
+
+our ($tests, $examples);
+
+# For testing only:
+use if $tests || $examples, 'File::Temp';
+use if $tests || $examples, 'File::DirCompare';
+#
+
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV == 2;
+usage: $0 [-examples] [-tests] [SOURCE TARGET]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+SOURCE TARGET
+    Source and target directories
+
+EOS
+
+
+### Input and Output
+
+copy_dirs(@ARGV);
+
+
+### Implementation
+
+# Find directories in the source tree and create corresponding
+# directories in the target tree if no such file exists yet.  At least
+# the parent directory of the target must exist beforehand.
+sub copy_dirs ($source, $target) {
+    find {
+        # Make sure the source path is not interpreted as a regex.
+        # # Make sure the source path is not interpreted as a regex.
+        wanted => sub {-d && s/^\Q$source\E/$target/ && !-e && mkdir},
+        no_chdir => 1}, $source;
+}
+
+
+### Examples and tests
+
+# This task has an interesting twist: The testing appears to be more
+# challenging than the implementation itself.
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        check_copy_dirs(
+            [qw(a/ a/b/ a/b/c/ a/b/c/1/ a/b/c/1/1.txt
+                a/b/c/4/ a/b/c/5/ a/b/c/5/5.txt
+                x/ x/y/ x/y/1/ x/y/2/ x/y/3/ x/y/4/ x/y/5/)],
+            [qw(x/ x/y/ x/y/1/ x/y/2/ x/y/3/ x/y/4/ x/y/5/)],
+            'a/b/c', 'x/y', 'example');
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+
+        check_copy_dirs(
+            [qw(a/ a/b/ a/b/1/ x/)],
+            [qw(x/ x/y/ x/y/1/)], 'a/b', 'x/y', 'target dir missing');
+
+        check_copy_dirs(
+            [qw(a/ a/b/ a/b/1/ a/b/1/1.txt a/b/2/ x/ x/y/ x/y/2)],
+            [qw(x/ x/y/ x/y/1/ x/y/2)], 'a/b', 'x/y', 'file exists');
+        
+        check_copy_dirs(
+            [qw(a/ a/b/ a/b/1/ a/b/1/1.txt a/b/2/ x/ x/y/ x/y/2/)],
+            [qw(x/ x/y/ x/y/1/ x/y/2/)], 'a/b', 'x/y', 'dir exists');
+
+        check_copy_dirs(
+            [qw(a.*/ a.*/b/ x/)],
+            [qw(x/ x/b/)], 'a.*', 'x', 'source directory name is a regex');
+	}
+
+    done_testing;
+    exit;
+}
+
+# A small test driver for copy_dirs:
+# - Create a working and an expectation directory.
+# - Populate the source directory tree in the working directory
+# - Populate the target directory tree - at least up to the target's
+#   parent directory - in the working directory.
+# - Populate the expectation directory.
+# - Call copy_dirs on the prepared source and target directories in the
+#   working directory.
+# - Compare the target directory in the working directory with the
+#   expected result in the expectation directory.
+#
+# Arguments:
+# - An array ref to a list of directories/files in the working directory
+#   where copy_dirs will be called.
+# - An array ref to a list of directories/files that are expected as the
+#   result after copy_dirs has been called.
+# - A source path within the working directory.
+# - A target path within the working directory.
+# - A test case title.
+#
+# Entries in a directory list ending with a slash are interpreted as
+# directories and as plain files otherwise.  Parent directories must be
+# specified and precede their content in the list.
+#
+# Limitations:
+# There are no provisions to check for expected errors in neither phase
+# of the test.
+sub check_copy_dirs ($work, $expect, $source, $target, $title) {
+    my $wrkdir = File::Temp->newdir();
+    my $expdir = File::Temp->newdir();
+
+    state sub populate ($wd, $content) {
+        opendir my $cwd, '.';
+        # Must not die in a working directory that is one of the
+        # temporary directories as the clean-up could fail otherwise.
+        eval {
+            chdir $wd;
+            m{/$} ? mkdir : open my $fh, '>', $_ for @$content;
+        };
+        chdir $cwd;
+        die $@ if $@;
+    };
+
+    # Safely populate working and expected directories.
+    eval {
+        populate($wrkdir, $work);
+        populate($expdir, $expect);
+    };
+    fail("populate: $title"), note($@), return if $@;
+
+    # Safely call copy_dirs.
+    eval {copy_dirs("$wrkdir/$source", "$wrkdir/$target")};
+    fail("call: $title"), note($@), return if $@;
+
+    # Compare the obtained with the expected result.
+    ok lives {
+        no warnings 'uninitialized';
+        # The sub given to File::DirCompare->compare is called for
+        # differing files only, i.e. it shall not be called at all.
+        File::DirCompare->compare("$wrkdir/$target", "$expdir/$target",
+            sub {die "@_ differing"});
+    }, $title or note $@;
+}