def test_not_calling_end_explodes(): F1 = lltype.FuncType([lltype.Signed], lltype.Signed) rgenop = RGenOp() sigtoken = rgenop.sigToken(F1) builder, gv_adder, [gv_x] = rgenop.newgraph(sigtoken, "adder") builder.start_writing() gv_result = builder.genop2("int_add", gv_x, rgenop.genconst(5)) builder.finish_and_return(sigtoken, gv_result) #builder.end() <--- the point ptr = gv_adder.revealconst(lltype.Ptr(F1)) py.test.raises(AssertionError, "testgengraph(ptr._obj.graph, [1])")