11 minute read

This discussion post looks at Test Engine from the lens of Power Fx. We will cover the following key topics:

  • What is Power Fx?: A low-code general-purpose programming language based on spreadsheet-like formulas, accessible to a wide range of users due to its roots in Excel.
  • Advanced Topics in Power Fx: Includes creating custom functions, integrating with external data sources, and optimizing performance for large-scale applications.
  • Extensibility Model: Leverages existing skills and libraries, encapsulates complexity, enhances collaboration, and facilitates integration with external systems.
  • Growing Language: Inspired by Excel’s Lambda functions, includes functions and modules for greater reuse and parameterization, enhancing flexibility and power.
  • Why Power Fx and Test Engine?: Provides a robust framework for testing and validating workflows and applications with declarative YAML definitions and new functions like Assert(). Power Platform Provider Model: Uses a common language for provider-specific functions like SimulateWorkflow(), SimulateDataverse(), and SimulateConnector().
  • Power Fx as an Intermediate Language in Generative AI: Bridges the gap between natural language and specific instructions, essential for generative AI applications.
  • Namespace Actions and Experimental Validation: Allows creation and validation of experimental actions before production, ensuring reliability and robustness.
  • Transferability of Skills Across the Platform: Consistent language and testing approach across Power Apps, Power Pages, and Power Automate, simplifying the learning curve and enhancing collaboration.

Join The Discussion

What aspects of Power Fx are you most curious about, and why?

  • What aspects of the Test Engine in Power Fx are you most curious about, and why?
  • What potential challenges do you foresee when using the Test Engine to validate workflows and applications?
  • What excites you most about the potential of using Power Fx as an intermediate language in generative AI for testing purposes?
  • How do you think the transferability of testing skills across Power Apps, Power Pages, and Power Automate could benefit your development process?
  • What features would you like to see added to the Test Engine to enhance its capabilities further?

Feel free to share your thoughts, questions, and experiences to help us all learn and grow together!

What is Power Fx?

Microsoft Power Fx is a low-code general-purpose programming language based on spreadsheet-like formulas. It is a strongly typed, declarative, and functional language, with imperative logic and state management available as needed. Power Fx started with Power Apps canvas and is being extracted to be used in more Microsoft Power Platform products. Its history from Excel makes it accessible to a wide range of users, from beginners to experienced developers.

Advanced Topics in Power Fx

For those already familiar with Power Fx, diving into advanced topics can significantly enhance the capabilities and efficiency of your applications. Here are some advanced topics and why they might be of interest:

  • Creating Custom Functions Creating custom functions allows developers to encapsulate complex logic into reusable components. This not only simplifies the development process but also ensures consistency and reduces the likelihood of errors. Custom functions can be tailored to specific business needs, making your applications more powerful and flexible.

  • Integrating with External Data Sources Integrating Power Fx with external data sources enables your applications to interact with a wide range of data, from databases to web services. This integration can enhance the functionality of your applications by providing real-time data access and updates. It also allows for more dynamic and responsive applications that can adapt to changing data.

  • Optimizing Performance for Large-Scale Applications As your applications grow in complexity and scale, performance optimization becomes crucial. Advanced topics in Power Fx include techniques for optimizing performance, such as efficient data handling, minimizing formula recalculations, and leveraging Power Fx’s built-in functions for better performance. These optimizations ensure that your applications remain responsive and efficient, even with large datasets and complex logic.

Extensibility Model

Power Fx’s extensibility model is one of its many compelling features. It allows developers to extend the language with custom functions and actions, making it highly adaptable to various scenarios. Here are some key aspects of the extensibility model:

  • Reuse the Skills You Already Have: Power Fx’s extensibility model allows developers to leverage their existing skills in other programming languages, such as C#. This means you can bring your knowledge and experience into the Power Fx environment, making it easier to create powerful and customized solutions.

  • Allow Reuse of Existing Libraries and Features: The extensibility model enables the integration of existing libraries and features into Power Fx. This allows developers to reuse tried-and-tested code, reducing development time and increasing reliability. By incorporating existing libraries, you can enhance the functionality of your Power Fx applications without reinventing the wheel.

  • Provide a Model to Encapsulate Complexity for Users of the Functions: One of the significant advantages of the extensibility model is its ability to encapsulate complexity. Developers can create custom functions that hide the intricate details of the underlying logic, providing a simple and user-friendly interface for end-users. This makes it easier for non-developers to use and benefit from advanced functionality without needing to understand the complexities behind it.

  • Enhance Collaboration and Consistency: By using the extensibility model, teams can create a consistent set of custom functions and actions that can be shared and reused across different projects. This promotes collaboration and ensures that best practices are followed, leading to more robust and maintainable applications.

  • Facilitate Integration with External Systems: The extensibility model allows for seamless integration with external systems and services. This means you can connect your Power Fx applications to a wide range of data sources and APIs, enhancing their capabilities and providing real-time data access.

  • Support for Advanced Scenarios: The extensibility model is designed to support advanced scenarios, such as creating domain-specific languages and custom workflows. This flexibility ensures that Power Fx can be adapted to meet the unique needs of different industries and use cases.

By understanding and leveraging the extensibility model, developers can create more powerful, flexible, and user-friendly applications with Power Fx. This model not only enhances the capabilities of the language but also makes it more accessible and valuable to a broader range of users.

Growing Language

The language is growing to include common features like functions and modules. These additions are designed to enhance the flexibility and power of Power Fx, allowing for greater reuse and parameterization.

  • Learnings from Excel’s Lambda Functions One of the key inspirations for Power Fx’s growth is Excel’s Lambda functions. Lambda functions in Excel allow users to create reusable, low-code functions that can take parameters. This capability has been incredibly powerful in Excel, enabling users to encapsulate complex logic into simple, reusable components. By bringing similar functionality to Power Fx, developers can create custom functions that can be reused across different parts of their applications, reducing redundancy and improving maintainability.

  • Creating Reusable Low-Code Functions: Power Fx is evolving to support the creation of reusable low-code functions. These functions can take parameters, allowing developers to create more flexible and adaptable logic. For example, a custom function to calculate sales tax can be created once and then reused wherever needed, simply by passing different parameters for the tax rate and the amount. This not only simplifies the development process but also ensures consistency and reduces the likelihood of errors.

  • Enhancing Flexibility and Power: The inclusion of functions and modules in Power Fx significantly enhances the language’s flexibility and power. Developers can create more sophisticated and adaptable applications by leveraging these features. Functions and modules enable the encapsulation of complex logic, making it easier to manage and reuse code. This not only improves the efficiency of the development process but also ensures that applications are more robust and maintainable.

By incorporating learnings from Excel’s Lambda functions and introducing common features like functions, Power Fx is evolving to become an even more powerful and flexible language. These enhancements allow for greater reuse and parameterization, enabling developers to create more sophisticated and adaptable applications with ease.

Why Power Fx and Test Engine?

The combination of Power Fx and Test Engine provides a robust framework for testing and validating workflows and applications.

By combining the strengths of Power Fx and the Test Engine, developers and makers can create robust, reliable, and adaptable applications. This combination not only enhances the testing process but also ensures that applications are thoroughly validated, reducing the risk of errors and improving overall quality.

Basics of Power Fx and Test Engine

The Test Engine in Power Fx allows users to create and run tests for their applications and workflows. This ensures that the logic and functionality of the applications are working as expected. The declarative YAML definition of a test case allows Power Fx expressions to be run before and after a test and define the test steps for each test case. The power of Power Fx’s variable system and conditional logic is available, making it a versatile tool for testing.

New Functions for Testing Context

New functions like Assert() are available for the testing context. These functions help validate the expected outcomes of tests, ensuring that the application behaves as intended. The provider model for different areas of the Power Platform requires different features, and predefined functions make this easier. For advanced scenarios, if the out-of-the-box interaction does not meet needs, developers can drop down to “no cliffs” extensibility to interact with Playwright directly for web-based tests as an example.

Advanced Testing Scenarios

Advanced users can leverage the Test Engine to create complex test scenarios, including edge cases and exception handling. This helps in identifying potential issues before they occur in a production environment. The flexibility of Power Fx and the Test Engine ensures that even the most intricate workflows can be thoroughly tested and validated.

Power Platform Provider Model

The Power Platform Provider Model of Test Engine build a common language provided by Power Fx. It allows functions to be specific to a Power Platform provider type while maintaining a consistent approach across tests. For example,

  • SimulateWorkflow(): can be used when starting a Cloud flow from a Power App, but also when calling a child flow in the context of PowerApps. This ensures that workflows are tested thoroughly in different contexts.

  • SimulateDataverse(): This function allows for the abstraction of complexity when interacting with Dataverse Create, Read, Update, and Delete operations. It simplifies the testing process by providing a straightforward way to simulate these interactions.

  • SimulateConnector(): This function allows for easy abstraction of expected responses when a connector returns expected results, edge cases, or exceptions. It ensures that all possible scenarios are tested, enhancing the reliability of the application.

All of this builds on the no cliffs extensibility model where you can leverage your skills to extend the tests. This could be done using C# Scripts or by creating new Power Fx functions to extend your test cases.

Power Fx as an Intermediate Language in Generative AI

As discussed in generative ai Power Fx can play a crucial role as an intermediate language in generative AI. It bridges the gap between natural language and specific instructions that can be validated. By combining the best of generative content and deterministic code actions, Power Fx enables the creation of precise and reliable workflows. This capability is particularly valuable in scenarios where natural language inputs need to be converted into actionable steps.

Role of Power Fx in Generative AI

Power Fx serves as an intermediate language that translates natural language inputs into specific, actionable instructions. This makes it an essential tool in the development of generative AI applications.

Advanced AI Integration

Advanced users can explore the integration of Power Fx with AI models to create intelligent applications that can understand and respond to natural language inputs.

Namespace Actions and Experimental Validation

Power Fx allows for the creation of namespace actions, enabling experimental actions to be validated before migrating to the TestEngine namespace. This feature ensures that new actions can be tested and refined in a controlled environment before being deployed in production. It enhances the reliability and robustness of workflows by allowing for thorough testing and validation.

Basics of Namespace Actions

Namespace actions in Power Fx allow users to organize and manage their custom actions. This makes it easier to maintain and update the actions as needed.

Advanced Validation Techniques

Advanced users can use namespace actions to create experimental features and validate them before deploying to production. This ensures that new features are thoroughly tested and reliable.

Transferability of Skills Across the Platform

One of the significant advantages of Power Fx is the transferability of skills across the Microsoft Power Platform. Users can apply their knowledge of Power Fx in Power Apps, Power Pages, and Power Automate, creating a common language and testing approach across the platform. This consistency simplifies the learning curve and enhances collaboration among teams.

Learning Power Fx Across the Platform

Power Fx is used across the Microsoft Power Platform, making it easy for users to transfer their skills from one application to another. This creates a consistent and efficient development experience.

Advanced Skill Transfer Techniques

Experienced users can leverage their knowledge of Power Fx to create complex solutions that span multiple applications within the Power Platform. This enhances collaboration and productivity across teams.