add tests for Kernel#caller_locations

Author: Nicolas Laurent

spec/ruby/core/kernel/caller_locations_spec.rb

@@ -22,11 +22,39 @@
     locations.length.should == 1
   end
 
+  it "can be called with a range" do
+    locations1 = caller_locations(0)
+    locations2 = caller_locations(2..4)
+    locations1[2..4].map(&:to_s).should == locations2.map(&:to_s)
+  end
+
+  it "can be called with a range whose end is negative" do
+    locations1 = caller_locations(0)
+    locations2 = caller_locations(2..-1)
+    locations3 = caller_locations(2..-2)
+    locations1[2..-1].map(&:to_s).should == locations2.map(&:to_s)
+    locations1[2..-2].map(&:to_s).should == locations3.map(&:to_s)
+  end
+
+  it "must return nil if omitting more locations than available" do
+    caller_locations(100).should == nil
+    caller_locations(100..-1).should == nil
+  end
+
+  it "must return [] if omitting exactly the number of locations available" do
+    omit = caller_locations(0).length
+    caller_locations(omit).should == []
+  end
+
   it 'returns the locations as Thread::Backtrace::Location instances' do
     locations = KernelSpecs::CallerLocationsTest.locations
 
     locations.each do |location|
       location.kind_of?(Thread::Backtrace::Location).should == true
     end
   end
+
+  it "must return the same locations when called with 1..-1 and when called with no arguments" do
+    caller_locations.map(&:to_s).should == caller_locations(1..-1).map(&:to_s)
+  end
 end