Add a new #filter alias for #select

* In Enumerable, Enumerator::Lazy, Array, Hash and Set
  [Feature #13784] [ruby-core:82285]
* Share specs for the various #select#select! methods and
  reuse them for #filter/#filter!.
* Add corresponding filter tests for select tests.
* Update NEWS.

[Fix GH-1824]

From: Alexander Patrick <adp90@case.edu>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62575 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 48 insertions, 24 deletions

diff --git a/spec/ruby/core/array/filter_spec.rb b/spec/ruby/core/array/filter_spec.rb
new file mode 100644
index 0000000000..d7c722e44c
--- /dev/null
+++ b/spec/ruby/core/array/filter_spec.rb
@@ -0,0 +1,14 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../shared/select', __FILE__)
+
+describe "Array#filter" do
+  it_behaves_like :array_select, :filter
+end
+
+describe "Array#filter!" do
+  it "returns nil if no changes were made in the array" do
+    [1, 2, 3].filter! { true }.should be_nil
+  end
+
+  it_behaves_like :keep_if, :filter!
+end
diff --git a/spec/ruby/core/array/select_spec.rb b/spec/ruby/core/array/select_spec.rb
index 8b83acaa5f..b7531c967d 100644
--- a/spec/ruby/core/array/select_spec.rb
+++ b/spec/ruby/core/array/select_spec.rb
@@ -1,30 +1,8 @@
 require File.expand_path('../../../spec_helper', __FILE__)
-require File.expand_path('../fixtures/classes', __FILE__)
-require File.expand_path('../shared/enumeratorize', __FILE__)
-require File.expand_path('../shared/keep_if', __FILE__)
-require File.expand_path('../../enumerable/shared/enumeratorized', __FILE__)
+require File.expand_path('../shared/select', __FILE__)
 
 describe "Array#select" do
-  it_behaves_like :enumeratorize, :select
-  it_behaves_like :enumeratorized_with_origin_size, :select, [1,2,3]
-
-  it "returns a new array of elements for which block is true" do
-    [1, 3, 4, 5, 6, 9].select { |i| i % ((i + 1) / 2) == 0}.should == [1, 4, 6]
-  end
-
-  it "does not return subclass instance on Array subclasses" do
-    ArraySpecs::MyArray[1, 2, 3].select { true }.should be_an_instance_of(Array)
-  end
-
-  it "properly handles recursive arrays" do
-    empty = ArraySpecs.empty_recursive_array
-    empty.select { true }.should == empty
-    empty.select { false }.should == []
-
-    array = ArraySpecs.recursive_array
-    array.select { true }.should == [1, 'two', 3.0, array, array, array, array, array]
-    array.select { false }.should == []
-  end
+  it_behaves_like :array_select, :select
 end
 
 describe "Array#select!" do
diff --git a/spec/ruby/core/array/shared/select.rb b/spec/ruby/core/array/shared/select.rb
new file mode 100644
index 0000000000..e09231415d
--- /dev/null
+++ b/spec/ruby/core/array/shared/select.rb
@@ -0,0 +1,32 @@
+require File.expand_path('../../../../spec_helper', __FILE__)
+require File.expand_path('../../fixtures/classes', __FILE__)
+require File.expand_path('../../shared/enumeratorize', __FILE__)
+require File.expand_path('../../shared/keep_if', __FILE__)
+require File.expand_path('../../../enumerable/shared/enumeratorized', __FILE__)
+
+describe :array_select, shared: true do
+  it_should_behave_like :enumeratorize
+
+  before :each do
+    @object = [1,2,3]
+  end
+  it_should_behave_like :enumeratorized_with_origin_size
+
+  it "returns a new array of elements for which block is true" do
+    [1, 3, 4, 5, 6, 9].send(@method) { |i| i % ((i + 1) / 2) == 0}.should == [1, 4, 6]
+  end
+
+  it "does not return subclass instance on Array subclasses" do
+    ArraySpecs::MyArray[1, 2, 3].send(@method) { true }.should be_an_instance_of(Array)
+  end
+
+  it "properly handles recursive arrays" do
+    empty = ArraySpecs.empty_recursive_array
+    empty.send(@method) { true }.should == empty
+    empty.send(@method) { false }.should == []
+
+    array = ArraySpecs.recursive_array
+    array.send(@method) { true }.should == [1, 'two', 3.0, array, array, array, array, array]
+    array.send(@method) { false }.should == []
+  end
+end