Update README.md

Author: m3y54m

README.md

@@ -6,7 +6,7 @@ Becoming an embedded engineer requires a broad understanding of both software an
 
 ## Roadmap
 
-![Embedded Systems Engineering Roadmap](https://github.com/m3y54m/Embedded-Engineering-Roadmap/releases/download/Rev.K-2023-07-31/Embedded-Engineering-Roadmap.png)
+![Embedded Systems Engineering Roadmap](https://github.com/m3y54m/Embedded-Engineering-Roadmap/releases/download/Rev.L-2023-07-31/Embedded-Engineering-Roadmap.png)
 
 ## Learning Resources
 
@@ -213,6 +213,10 @@ Becoming an embedded engineer requires a broad understanding of both software an
 
 ### Testing
 
+### Unit Testing
+
+- [Embedded C/C++ Unit Testing with Mocks](https://interrupt.memfault.com/blog/unit-test-mocking)
+
 ### Embedded AI
 
 ### Security & Cryptography