From aaba081e2438f2ffe29c204e55e8ce5315423b5b Mon Sep 17 00:00:00 2001
From: Simon Shine <shreddedglory@gmail.com>
Date: Fri, 10 May 2019 14:47:47 +0200
Subject: [PATCH] custom-set: Stub, order of methods, rename some methods
 (#286)

---
 .../custom-set/.meta/solutions/CustomSet.pm   |  83 ++++------
 exercises/custom-set/CustomSet.pm             |  73 +++++++++
 exercises/custom-set/custom-set.t             | 148 +++++++++---------
 3 files changed, 179 insertions(+), 125 deletions(-)
 create mode 100644 exercises/custom-set/CustomSet.pm

diff --git a/exercises/custom-set/.meta/solutions/CustomSet.pm b/exercises/custom-set/.meta/solutions/CustomSet.pm
index 95a75c6d..37fdd047 100644
--- a/exercises/custom-set/.meta/solutions/CustomSet.pm
+++ b/exercises/custom-set/.meta/solutions/CustomSet.pm
@@ -1,91 +1,74 @@
 package CustomSet;
-
 use strict;
 use warnings;
 
 sub new {
-    my $class = shift;
-
+    my ($class, @members) = @_;
     my %set;
-    @set{ @_ } = ();
-
+    @set{ @members } = ();
     bless \%set, $class;
 }
 
 sub add {
-    my( $self, $new ) = @_;
-
-    $self->{$new} = 1;
+    my ($self, $member) = @_;
+    $self->{$member} = 1;
     return $self;
 }
 
-sub delete :method {
-    my( $self, $member ) = @_;
-
+sub remove {
+    my ($self, $member) = @_;
     delete $self->{$member};
     return $self;
 }
 
-sub union {
-    my( $self, $other ) = @_;
-
-    return __PACKAGE__->new( keys %$self, keys %$other );
+sub is_empty {
+    my ($self) = @_;
+    return !%$self;
 }
 
-sub difference {
-    my( $self, $other ) = @_;
-
-    return __PACKAGE__->new( grep { ! $other->is_member($_) } keys %$self );
+sub is_member {
+    my ($self, $member) = @_;
+    return exists $self->{$member};
 }
 
-
-sub is_disjoint {
-    my( $self, $other ) = @_;
-
-    return $self->intersect( $other )->size() == 0;
+sub size {
+    my ($self) = @_;
+    return scalar keys %$self;
 }
 
-sub empty {
-    my $self = shift;
+sub to_list {
+    my ($self) = @_;
+    return keys %$self;
+}
 
-    %$self = ();
-    return $self;
+sub union {
+    my ($self, $other) = @_;
+    return __PACKAGE__->new( keys %$self, keys %$other );
 }
 
 sub intersect {
-    my( $self, $other ) = @_;
-
+    my ($self, $other) = @_;
     return __PACKAGE__->new( grep { $self->is_member($_) } keys %$other );
 }
 
-sub is_member {
-    my( $self, $member ) = @_;
-
-    return exists $self->{$member};
+sub difference {
+    my ($self, $other) = @_;
+    return __PACKAGE__->new( grep { !$other->is_member($_) } keys %$self );
 }
 
-sub size {
-    my $self = shift;
-
-    return scalar keys %$self;
+sub is_disjoint {
+    my ($self, $other) = @_;
+    return $self->intersect($other)->is_empty;
 }
 
 sub is_subset {
-    my( $self, $other ) = @_;
-
-    return $self->intersect( $other )->size() == $other->size();
-}
-
-sub to_list {
-    my $self = shift;
-
-    return keys %$self;
+    my ($self, $other) = @_;
+    return $other->difference($self)->is_empty;
 }
 
 sub is_equal {
-    my( $self, $other ) = @_;
-
-    return $self->intersect($other)->size() == $self->size() && $self->size() == $other->size();
+    my ($self, $other) = @_;
+    return $self->is_subset($other) && $other->is_subset($self);
 }
 
 1;
diff --git a/exercises/custom-set/CustomSet.pm b/exercises/custom-set/CustomSet.pm
new file mode 100644
index 00000000..4ebd473e
--- /dev/null
+++ b/exercises/custom-set/CustomSet.pm
@@ -0,0 +1,73 @@
+package CustomSet;
+use strict;
+use warnings;
+
+# Replace `...` with a correct implementation.
+# https://perldoc.pl/perlsyn#The-Ellipsis-Statement
+
+sub new {
+    my ($class, @members) = @_;
+    ...;
+}
+
+sub add {
+    my ($self, $member) = @_;
+    ...;
+}
+
+sub remove {
+    my ($self, $member) = @_;
+    ...;
+}
+
+sub is_empty {
+    my ($self) = @_;
+    ...;
+}
+
+sub is_member {
+    my ($self, $member) = @_;
+    ...;
+}
+
+sub size {
+    my ($self) = @_;
+    ...;
+}
+
+sub to_list {
+    my ($self) = @_;
+    ...;
+}
+
+sub union {
+    my ($self, $other) = @_;
+    ...;
+}
+
+sub intersect {
+    my ($self, $other) = @_;
+    ...;
+}
+
+sub difference {
+    my ($self, $other) = @_;
+    ...;
+}
+
+sub is_disjoint {
+    my ($self, $other) = @_;
+    ...;
+}
+
+sub is_subset {
+    my ($self, $other) = @_;
+    ...;
+}
+
+sub is_equal {
+    my ($self, $other) = @_;
+    ...;
+}
+
+1;
diff --git a/exercises/custom-set/custom-set.t b/exercises/custom-set/custom-set.t
index 0e55ba6d..f858c759 100755
--- a/exercises/custom-set/custom-set.t
+++ b/exercises/custom-set/custom-set.t
@@ -10,9 +10,12 @@ my $module = 'CustomSet';
 
 use_ok($module) or BAIL_OUT("You need to create a module called $module.pm");
 
-foreach my $f (qw/new delete difference is_disjoint empty intersect
-		  is_member add size is_subset to_list union is_equal/) {
-    can_ok($module, $f) or BAIL_OUT("You need to implement the function '$f'");
+for my $method (qw(
+    new add remove is_empty
+    is_member size to_list
+    union intersect difference
+    is_disjoint is_equal is_subset)) {
+    can_ok($module, $method) or BAIL_OUT("You need to implement the method '$method'");
 }
 
 sub set { return $module->new(@_) };
@@ -23,15 +26,65 @@ subtest 'Tested new()' => sub {
     isa_ok( $module->new(), $module, "return value of new()" );
 };
 
-subtest 'Tested equal()' => sub {
-    plan tests => 6;
+subtest 'Tested add()' => sub {
+    plan tests => 4;
 
-    ok( set(1,3)->is_equal( set(3,1) ), "order doesn't matter" );
-    ok( set()->is_equal( set() ), "empty sets are equal" );
-    ok( ! set(1..3)->is_equal( set(3..5) ), "different sets are not equal" );
-    ok( ! set()->is_equal( set(1..3) ), "empty set is not equal to non-empty set" );
-    ok( ! set(1..3)->is_equal( set() ), "non-empty set is not equal to empty set" );
-    ok( ! set(1..4)->is_equal( set(3..6) ), "partial subsets are not equal" );
+    isa_ok( set()->add(1), $module, "return value of add()" );
+    ok( set()->add(1)->is_equal( set(1) ), "adding to empty set" );
+    ok( set(1,2,4)->add(3)->is_equal( set(1..4) ), "adding to non-empty set" );
+    ok( set(1,2,3)->add(3)->is_equal( set(1..3) ), "adding existing member is noop" );
+};
+
+subtest 'Tested remove()' => sub {
+    plan tests => 3;
+
+    isa_ok( set(3,2,1)->remove(2), $module, "return value of remove()" );
+    ok( set(3,2,1)->remove(2)->is_equal( set(1,3) ), "removing single element" );
+    ok( set(3,2,1)->remove(4)->is_equal( set(1..3) ), "removing non-existant element" );
+};
+
+subtest 'Tested is_empty()' => sub {
+    plan tests => 2;
+
+    ok( set()->is_empty(), "sets with no elements are empty" );
+    ok( !set(1)->is_empty(), "sets with elements are not empty" );
+};
+
+subtest 'Tested is_member()' => sub {
+    plan tests => 4;
+
+    ok( set(1,2,3)->is_member(2), "element is member" );
+    ok( set(1..10)->is_member(10), "edge element is also member" );
+    ok( ! set(1..10)->is_member(11), "element is not member" );
+    ok( ! set()->is_member(1), "nothing is member of the empty set" );
+};
+
+subtest 'Tested size()' => sub {
+    plan tests => 3;
+
+    is( set()->size(), 0, "size of empty set is 0" );
+    is( set(1..3)->size(), 3, "size of set with 3 members is 3!" );
+    is( set(1,2,3,2)->size(), 3, "size of set with 3 members is still 3!" );
+};
+
+subtest 'Tested to_list()' => sub {
+    plan tests => 3;
+
+    is_deeply( [ sort +set()->to_list() ], [], "empty set results in empty list" );
+    is_deeply( [ sort +set(1..3)->to_list() ], [1,2,3], "set with elements results in list with elements" );
+    is_deeply( [ sort +set(3,1,2,1)->to_list() ], [1,2,3], "set with duplicate elements still results in list with uniq elements" );
+};
+
+subtest 'Tested union()' => sub {
+    plan tests => 7;
+
+    isa_ok( set()->union( set() ), $module, "return value of union()" );
+    ok( set()->union( set() )->is_equal( set() ), "union of empty sets is an empty set" );
+    ok( set(2)->union( set() )->is_equal( set(2) ), "union of non-empty set and empty set is non-empty set" );
+    ok( set()->union( set(2) )->is_equal( set(2) ), "union of empty set and non-empty set is non-empty set" );
+    ok( set(1,3)->union( set(3,1) )->is_equal( set(1,3) ), "union with self is self" );
+    ok( set(1,3)->union( set(2,4) )->is_equal( set(1..4) ), "small union" );
+    ok( set(1..10, 20..30)->union( set(5..25) )->is_equal( set(1..30) ), "large union" );
 };
 
 subtest 'Tested intersect()' => sub {
@@ -43,24 +96,7 @@ subtest 'Tested intersect()' => sub {
     ok( set(1..3)->intersect( set(4..6) )->is_equal( set() ), "nothing in common" );
     ok( set(1,3,5,7,9)->intersect( set(3..7) )->is_equal( set(3,5,7) ), "intersect with odd numbers" );
     ok( set()->intersect( set() )->is_equal( set() ), "an empty set is an empty set" );
-    ok( set(1..3)->intersect( set(3) )->is_equal( set(3) ), "Intersect with unary set results in unary set" );  
-};
-
-subtest 'Tested delete()' => sub {
-    plan tests => 3;
-
-    isa_ok( set(3,2,1)->delete(2), $module, "return value of delete()" );
-    ok( set(3,2,1)->delete(2)->is_equal( set(1,3) ), "removing single element" );
-    ok( set(3,2,1)->delete(4)->is_equal( set(1..3) ), "removing non-existant element" );
-};
-
-subtest 'Tested add()' => sub {
-    plan tests => 4;
-
-    isa_ok( set()->add(1), $module, "return value of add()" );
-    ok( set()->add(1)->is_equal( set(1) ), "adding to empty set" );
-    ok( set(1,2,4)->add(3)->is_equal( set(1..4) ), "adding to non-empty set" );
-    ok( set(1,2,3)->add(3)->is_equal( set(1..3) ), "adding existing member is noop" );
+    ok( set(1..3)->intersect( set(3) )->is_equal( set(3) ), "Intersect with unary set results in unary set" );
 };
 
 subtest 'Tested difference()' => sub {
@@ -84,35 +120,6 @@ subtest 'Tested is_disjoint()' => sub {
     ok( set(1..3)->is_disjoint( set() ), "a non-empty set is disjoint to an empty set" );
 };
 
-subtest 'Tested empty()' => sub {
-    plan tests => 4;
-
-    isa_ok( set()->empty(), $module, "return value of empty()" );
-    ok( set()->empty()->is_equal( set() ), "emptying empty set results in an empty set" );
-    ok( set(1..3)->empty()->is_equal( set() ), "set empty after emptying (duh!)" );
-    
-    my $set = set(1..3);
-    $set->empty();
-    ok( $set->is_equal( set() ), "not just an empty set returned, but set was emptied" ); 
-};
-
-subtest 'Tested is_member()' => sub {
-    plan tests => 4;
-
-    ok( set(1,2,3)->is_member(2), "element is member" );
-    ok( set(1..10)->is_member(10), "edge element is also member" );
-    ok( ! set(1..10)->is_member(11), "element is not member" );
-    ok( ! set()->is_member(1), "nothing is member of the empty set" );
-};
-
-subtest 'Tested size()' => sub {
-    plan tests => 3;
-
-    is( set()->size(), 0, "size of empty set is 0" );
-    is( set(1..3)->size(), 3, "size of set with 3 members is 3!" );
-    is( set(1,2,3,2)->size(), 3, "size of set with 3 members is still 3!" );
-};
-
 subtest 'Tested is_subset()' => sub {
     plan tests => 8;
 
@@ -126,22 +133,13 @@ subtest 'Tested is_subset()' => sub {
     ok( ! set(1..10)->is_subset( set(1..3, 11) ), "smaller number of elements but still not a subset" );
 };
 
-subtest 'Tested union()' => sub {
-    plan tests => 7;
-    
-    isa_ok( set()->union( set() ), $module, "return value of union()" );
-    ok( set()->union( set() )->is_equal( set() ), "union of empty sets is an empty set" );
-    ok( set(2)->union( set() )->is_equal( set(2) ), "union of non-empty set and empty set is non-empty set" );
-    ok( set()->union( set(2) )->is_equal( set(2) ), "union of empty set and non-empty set is non-empty set" );
-    ok( set(1,3)->union( set(3,1) )->is_equal( set(1,3) ), "union with self is self" );
-    ok( set(1,3)->union( set(2,4) )->is_equal( set(1..4) ), "small union" );
-    ok( set(1..10, 20..30)->union( set(5..25) )->is_equal( set(1..30) ), "large union" );
-};
-
-subtest 'Tested to_list()' => sub {
-    plan tests => 3;
+subtest 'Tested equal()' => sub {
+    plan tests => 6;
 
-    is_deeply( [ sort +set()->to_list() ], [], "empty set results in empty list" );
-    is_deeply( [ sort +set(1..3)->to_list() ], [1,2,3], "set with elements results in list with elements" );
-    is_deeply( [ sort +set(3,1,2,1)->to_list() ], [1,2,3], "set with duplicate elements still results in list with uniq elements" );
+    ok( set(1,3)->is_equal( set(3,1) ), "order doesn't matter" );
+    ok( set()->is_equal( set() ), "empty sets are equal" );
+    ok( ! set(1..3)->is_equal( set(3..5) ), "different sets are not equal" );
+    ok( ! set()->is_equal( set(1..3) ), "empty set is not equal to non-empty set" );
+    ok( ! set(1..3)->is_equal( set() ), "non-empty set is not equal to empty set" );
+    ok( ! set(1..4)->is_equal( set(3..6) ), "partial subsets are not equal" );
 };