1 files changed, 69 insertions, 0 deletions
diff --git a/spec/ruby/core/thread/backtrace_spec.rb b/spec/ruby/core/thread/backtrace_spec.rb
new file mode 100644
index 0000000000..15bb29a349
--- /dev/null
+++ b/spec/ruby/core/thread/backtrace_spec.rb
@@ -0,0 +1,69 @@
+require_relative '../../spec_helper'
+
+describe "Thread#backtrace" do
+  it "returns the current backtrace of a thread" do
+    t = Thread.new do
+      begin
+        sleep
+      rescue
+      end
+    end
+
+    Thread.pass while t.status && t.status != 'sleep'
+
+    backtrace = t.backtrace
+    backtrace.should be_kind_of(Array)
+    backtrace.first.should =~ /[`'](?:Kernel#)?sleep'/
+
+    t.raise 'finish the thread'
+    t.join
+  end
+
+  it "returns nil for dead thread" do
+    t = Thread.new {}
+    t.join
+    t.backtrace.should == nil
+  end
+
+  it "returns an array (which may be empty) immediately after the thread is created" do
+    t = Thread.new { sleep }
+    backtrace = t.backtrace
+    t.kill
+    t.join
+    backtrace.should be_kind_of(Array)
+  end
+
+  it "can be called with a number of locations to omit" do
+    locations1 = Thread.current.backtrace
+    locations2 = Thread.current.backtrace(2)
+    locations1[2..-1].length.should == locations2.length
+    locations1[2..-1].map(&:to_s).should == locations2.map(&:to_s)
+  end
+
+  it "can be called with a maximum number of locations to return as second parameter" do
+    locations1 = Thread.current.backtrace
+    locations2 = Thread.current.backtrace(2, 3)
+    locations1[2..4].map(&:to_s).should == locations2.map(&:to_s)
+  end
+
+  it "can be called with a range" do
+    locations1 = Thread.current.backtrace
+    locations2 = Thread.current.backtrace(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
+    Thread.current.backtrace(2..-1).should == Thread.current.backtrace[2..-1]
+    Thread.current.backtrace(2..-2).should == Thread.current.backtrace[2..-2]
+  end
+
+  it "returns nil if omitting more locations than available" do
+    Thread.current.backtrace(100).should == nil
+    Thread.current.backtrace(100..-1).should == nil
+  end
+
+  it "returns [] if omitting exactly the number of locations available" do
+    omit = Thread.current.backtrace.length
+    Thread.current.backtrace(omit).should == []
+  end
+end