Updated Understanding and debugging Nimbus EVM JSON tests (markdown)

Understanding-and-debugging-Nimbus-EVM-JSON-tests.md

@@ -9,7 +9,7 @@ Run example:
 mkdir -p build
 nim c -r -o:build/decompile_smart_contract examples/decompile_smart_contract.nim
 ```
-
+## General State Tests
 Run Ethereum [JSON-based general state tests](https://github.com/ethereum/tests/):
 ```
 mkdir -p build
@@ -21,13 +21,31 @@ Build and run an individual test (with tracing enabled):
 ```
 nim c -r -d:chronicles_log_level=TRACE -o:build/test_generalstate_json tests/test_generalstate_json.nim stAttackTest/ContractCreationSpam.json
 ```
-(this particular test needs to be commented out of "tests/test_generalstate_failing.nim" before running it)
-
 Individual tests are default only tested on Frontier fork. You can change the fork with `--fork:`, e.g.:
 ```
 nim c -d:release -r -o:build/test_generalstate_json tests/test_generalstate_json.nim stCallCreateCallCodeTest/Call1024BalanceTooLow.json --fork:Byzantium
 ```
 
+Subtest for this individual test can be selected using `--index:number`, and the number start from 1.
+```
+nim c -d:release -r -o:build/test_generalstate_json tests/test_generalstate_json.nim stSStoreTest/InitCollision.json --fork:Byzantium --index:1
+```
+
+Every time you run this individual test, it will dump debugging data/VM trace in json formatted file. 
+If you only need short dump instead of long dump, you can use `--trace:on/off` or `--trace:true/false`.
+
+## Block Chain Tests
+
+The same CLI are used both by General State Tests and Block Chain Tests. They differ in the input path and doesn't accept fork argument.
+```
+nim c -d:release -r tests/test_blockchain_json.nim GeneralStateTests/stSStoreTest/InitCollision.json --index:1
+```
+Addition input path prefix are:
+* GeneralStateTests
+* InvalidBlocks
+* TransitionTests
+* ValidBlocks
+
 ## VMTests
 
 ### JSON structure