A framework and tool support for the systematic testing of model-based specifications

Formal specifications can precisely and unambiguously define the required behavior of a software system or component. However, formal specifications are complex artifacts that need to be verified to ensure that they are consistent, complete, and validated against the requirements. Specification testing or animation tools exist to assist with this by allowing the specifier to interpret or execute the specification. However, currently little is known about how to do this effectively. This article presents a framework and tool support for the systematic testing of formal, model-based specifications. Several important generic properties that should be satisfied by model-based specifications are first identified. Following the idea of mutation analysis, we then use variants or mutants of the specification to check that these properties are satisfied. The framework also allows the specifier to test application-specific properties. All properties are tested for a range of states that are defined by the tester in the form of a testgraph, which is a directed graph that partially models the states and transitions of the specification being tested. Tool support is provided for the generation of the mutants, for automatically traversing the testgraph and executing the test cases, and for reporting any errors. The framework is demonstrated on a small specification and its application to three larger specifications is discussed. Experience indicates that the framework can be used effectively to test small to medium-sized specifications and that it can reveal a significant number of problems in these specifications.

Danger zones and hot spots: Traversing Canadian and Australian narratives of urban multiculturalism

The ethnicity of urban space has long been an element in the burgeoning discourse of national multiculturalisms; so much so that spatial theorist Edward Soja uses the term “ethni-city” to speak of so-called postmodern or postcolonial urban geographies (239). In our focus on the urban, we point to both the conceptual and material thresholds of multiculturalism within the borders of the city, as well as the internal urban/suburban borders that delineate belonging. These are often as strongly patrolled as larger national borders. In taking up Sneja Gunew’s call in Haunted Nations for comparative and critical work on multiculturalisms, this paper offers preliminary and exploratory avenues and points of departure, and aims to particularise the multicultural as an encounter and experience that is regulated spatially and corporeally.