Added src directory

src/about_exceptions.rb

@@ -0,0 +1,60 @@
+require 'edgecase'
+
+class AboutExceptions < EdgeCase::Koan
+
+  class MySpecialError < RuntimeError
+  end
+
+  def test_exceptions_inherit_from_Exception
+    assert_equal __(RuntimeError), MySpecialError.ancestors[1]
+    assert_equal __(StandardError), MySpecialError.ancestors[2]
+    assert_equal __(Exception), MySpecialError.ancestors[3]
+    assert_equal __(Object), MySpecialError.ancestors[4]
+  end
+
+  def test_rescue_clause
+    result = nil
+    begin
+      fail "Oops"
+    rescue StandardError => ex
+      result = :exception_handled
+    end
+
+    assert_equal __(:exception_handled), result
+
+    assert ex.is_a?(StandardError), "Failure message."
+    assert ex.is_a?(RuntimeError), "Failure message."
+
+    assert RuntimeError.ancestors.include?(StandardError),
+      "RuntimeError is a subclass of StandardError"
+    
+    assert_equal __("Oops"), ex.message
+  end
+
+  def test_raising_a_particular_error
+    result = nil
+    begin
+      # 'raise' and 'fail' are synonyms
+      raise MySpecialError, "My Message"
+    rescue MySpecialError => ex
+      result = :exception_handled
+    end
+
+    assert_equal __(:exception_handled), result
+    assert_equal __("My Message"), ex.message
+  end
+
+  def test_ensure_clause
+    result = nil
+    begin
+      fail "Oops"
+    rescue StandardError => ex
+      # no code here
+    ensure
+      result = :always_run
+    end
+
+    assert_equal __(:always_run), result
+  end
+
+end