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

spec/ruby/library/set/filter_spec.rb

@@ -0,0 +1,6 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../shared/select', __FILE__)
+
+describe "Set#filter!" do
+  it_behaves_like :set_select_bang, :filter!
+end

spec/ruby/library/set/select_spec.rb

@@ -1,42 +1,6 @@
 require File.expand_path('../../../spec_helper', __FILE__)
-require 'set'
+require File.expand_path('../shared/select', __FILE__)
 
 describe "Set#select!" do
-  before :each do
-    @set = Set["one", "two", "three"]
-  end
-
-  it "yields every element of self" do
-    ret = []
-    @set.select! { |x| ret << x }
-    ret.sort.should == ["one", "two", "three"].sort
-  end
-
-  it "keeps every element from self for which the passed block returns true" do
-    @set.select! { |x| x.size != 3 }
-    @set.size.should eql(1)
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
-
-  it "returns self when self was modified" do
-    @set.select! { false }.should equal(@set)
-  end
-
-  it "returns nil when self was not modified" do
-    @set.select! { true }.should be_nil
-  end
-
-  it "returns an Enumerator when passed no block" do
-    enum = @set.select!
-    enum.should be_an_instance_of(Enumerator)
-
-    enum.each { |x| x.size != 3 }
-
-    @set.should_not include("one")
-    @set.should_not include("two")
-    @set.should include("three")
-  end
+  it_behaves_like :set_select_bang, :select!
 end

spec/ruby/library/set/shared/select.rb

@@ -0,0 +1,42 @@
+require File.expand_path('../../../../spec_helper', __FILE__)
+require 'set'
+
+describe :set_select_bang, shared: true do
+  before :each do
+    @set = Set["one", "two", "three"]
+  end
+
+  it "yields every element of self" do
+    ret = []
+    @set.send(@method) { |x| ret << x }
+    ret.sort.should == ["one", "two", "three"].sort
+  end
+
+  it "keeps every element from self for which the passed block returns true" do
+    @set.send(@method) { |x| x.size != 3 }
+    @set.size.should eql(1)
+
+    @set.should_not include("one")
+    @set.should_not include("two")
+    @set.should include("three")
+  end
+
+  it "returns self when self was modified" do
+    @set.send(@method) { false }.should equal(@set)
+  end
+
+  it "returns nil when self was not modified" do
+    @set.send(@method) { true }.should be_nil
+  end
+
+  it "returns an Enumerator when passed no block" do
+    enum = @set.send(@method)
+    enum.should be_an_instance_of(Enumerator)
+
+    enum.each { |x| x.size != 3 }
+
+    @set.should_not include("one")
+    @set.should_not include("two")
+    @set.should include("three")
+  end
+end

spec/ruby/library/set/sortedset/filter_spec.rb

@@ -0,0 +1,7 @@
+require File.expand_path('../../../../spec_helper', __FILE__)
+require File.expand_path('../shared/select', __FILE__)
+require 'set'
+
+describe "SortedSet#filter!" do
+  it_behaves_like :sorted_set_select_bang, :filter!
+end

spec/ruby/library/set/sortedset/select_spec.rb

@@ -1,35 +1,7 @@
 require File.expand_path('../../../../spec_helper', __FILE__)
+require File.expand_path('../shared/select', __FILE__)
 require 'set'
 
 describe "SortedSet#select!" do
-  before :each do
-    @set = SortedSet["one", "two", "three"]
-  end
-
-  it "yields each Object in self in sorted order" do
-    res = []
-    @set.select! { |x| res << x }
-    res.should == ["one", "two", "three"].sort
-  end
-
-  it "keeps every element from self for which the passed block returns true" do
-    @set.select! { |x| x.size != 3 }
-    @set.to_a.should == ["three"]
-  end
-
-  it "returns self when self was modified" do
-    @set.select! { false }.should equal(@set)
-  end
-
-  it "returns nil when self was not modified" do
-    @set.select! { true }.should be_nil
-  end
-
-  it "returns an Enumerator when passed no block" do
-    enum = @set.select!
-    enum.should be_an_instance_of(Enumerator)
-
-    enum.each { |x| x.size != 3 }
-    @set.to_a.should == ["three"]
-  end
+  it_behaves_like :sorted_set_select_bang, :select!
 end

spec/ruby/library/set/sortedset/shared/select.rb

@@ -0,0 +1,35 @@
+require File.expand_path('../../../../../spec_helper', __FILE__)
+require 'set'
+
+describe :sorted_set_select_bang, shared: true do
+  before :each do
+    @set = SortedSet["one", "two", "three"]
+  end
+
+  it "yields each Object in self in sorted order" do
+    res = []
+    @set.send(@method) { |x| res << x }
+    res.should == ["one", "two", "three"].sort
+  end
+
+  it "keeps every element from self for which the passed block returns true" do
+    @set.send(@method) { |x| x.size != 3 }
+    @set.to_a.should == ["three"]
+  end
+
+  it "returns self when self was modified" do
+    @set.send(@method) { false }.should equal(@set)
+  end
+
+  it "returns nil when self was not modified" do
+    @set.send(@method) { true }.should be_nil
+  end
+
+  it "returns an Enumerator when passed no block" do
+    enum = @set.send(@method)
+    enum.should be_an_instance_of(Enumerator)
+
+    enum.each { |x| x.size != 3 }
+    @set.to_a.should == ["three"]
+  end
+end