clean up 1.8 and 1.9 compatibility

Author: quix

test/linalg-test.rb

@@ -46,10 +46,16 @@ def assert_nothing_raised
          begin
             yield
          rescue => e
-            assert_block("raised in assert_nothing_raised: #{e.inspect}") {
+            assert_block("Exception raised:\n #{e.inspect}") {
                false
             }
+            return
          end
+         assert(true)
+      end
+
+      def assert_not_nil(*args, &block)
+         refute_nil(*args, &block)
       end
    end
 end

test/tc_nullspace.rb

@@ -37,7 +37,7 @@ def test_typical
                end
                a.replace_column(c0, a.column(c1))
                ns2 = a.nullspace(EPSILON)
-               refute_nil(ns2)
+               assert_not_nil(ns2)
                assert_equal(ns2.hsize, 1)
                assert_equal(a.hsize, a.rank + a.nullity)
             end