docs: add documentation for executable unit validation.

This commit introduces a new documentation file that explains the concept of executable unit validation and its importance in ensuring the accuracy and executability of generated code in AutoDev. The documentation covers various validation mechanisms implemented or planned for different functionalities, such as SQL syntax validation, unit test execution, and functional code generation validation.

Author: phodal

docs/patterns/executable-unit-validation.md

@@ -0,0 +1,31 @@
+---
+layout: default
+title: Executable Unit Validation
+nav_order: 4
+parent: Design Patterns
+---
+
+Executable unit validation refers to the process of testing and verifying the generated code to ensure that it can be
+compiled and executed by the compiler. The aim of executable unit validation is to enhance the accuracy and
+executability of the generated code, ensuring that the generated code units meet expectations and can be effectively
+utilized.
+
+In AutoDev, corresponding to functionalities such as SQL combined with the database, unit testing, and functional code
+generation, we have preliminarily designed the following validation mechanisms:
+
+- Unit Test Syntax (TODO): Check whether the generated unit test code complies with language syntax specifications to
+  ensure it can be compiled correctly by the compiler.
+- Unit Test Execution: Execute the generated unit test cases to test the generated code, ensuring it can be compiled and
+  executed correctly by the compiler.
+- SQL Syntax Validation: Generate SQL statements based on different model capabilities and handle any resulting errors.
+- SQL Schema Validation (TODO): Combine with the connected database to check the generated SQL statements, ensuring they
+  comply with the database schema specifications.
+- Functional Code Generation Validation (TODO): Adopt a test-driven validation mechanism to check the generated code,
+  ensuring it meets development requirements and can be compiled correctly by the compiler.
+- Frontend Code Generation Validation (TODO): Check the generated frontend code to ensure correctness in imports,
+  syntax, etc.
+
+Considering that unit tests are directly executable, in AutoDev, we directly execute unit tests (`RunService`), and with
+a fast enough IDE, the validation process is generally rapid. Through the aforementioned validation mechanisms, we can
+effectively enhance the accuracy and executability of the generated code, ensuring that the generated code units meet
+expectations and can be effectively utilized.