Update yenchihliao.md

yenchihliao.md

@@ -70,6 +70,7 @@ web3 developer, 朋友推坑第一次嘗試參加
 Finished week0 and week1
 
 The week1 contains a lot of useful info, despite the vedio recording of somehow hard to focus on. The [quiz](https://ethereum.org/zh/quizzes/) is extremely helpful
+
 Picked up/strengthened some key concepts
 - Pretty Good Privacy (PGP) protocol, Signal protocol (both asymatric)
 - Stacking offline panelty
@@ -111,4 +112,16 @@ Picked up/strengthened some key concepts
 - Justification: 2/3 of validators attested
 - Finialize: Justifying a justified block
 
+### 2025.02.12
+Finished week4
+
+It's talking about all the different ways/frameworks of testing. Without some concrete examples, it's really hard to get the merits of each of them
+
+Picked up/strengthened some key concepts
+- Execution Spec tests: Generate tests for EL clients
+- Fuzzy Differential State Testing: Run a fuzzy smart contract and compares resulting state root of differenet clients
+- Blockchain Testing: Similar to the previous test but on the scope of block hashes
+- Hive Test: generate CL and EL for specific tests
+- Shallow-fork: Early hard-fork from limited nodes
+
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