Constructing component-based software using reusable components is becoming a widely used approach. Since the quality of a component-based system is highly dependent on the quality of its components, component quality validation becomes very critical to both component vendors and users. Effectively validating component quality needs adequate test models and testing coverage criteria. This paper proposes an adequate test model and test coverage criteria for component validation. The paper discusses a dynamic approach to analyze component test coverage based on the proposed test model and test coverage criteria. The major contribution of this paper is its dynamic test coverage analysis solution to monitor API-based component validation and reuse. The paper reports the recent development efforts of a component test coverage analysis tool, and presents an application example.