update ssz test format and fix uint sizes

specs/test_formats/ssz/uint.md

@@ -5,22 +5,19 @@ SSZ supports encoding of uints up to 32 bytes. These are considered to be basic
 ## Test case format
 
 ```yaml
-TODO: old format
-# type: "uintN"      -- string, where N is one of [8, 16, 32, 64, 128, 256]
-# valid: bool        -- expected validity of the input data
-# ssz: bytes         -- string, input data, hex encoded, with prefix 0x
-# tags: List[string] -- description of test case, in the form of a list of labels
+type: "uintN"      -- string, where N is one of [8, 16, 32, 64, 128, 256]
+valid: bool        -- expected validity of the input data
+value: string      -- string, decimal encoding, to support up to 256 bit integers
+ssz: bytes         -- string, input data, hex encoded, with prefix 0x
+tags: List[string] -- description of test case, in the form of a list of labels
 ```
 
 ## Condition
 
-- Encoding: After encoding the given input number, the
-- Decoding: After decoding the given `output` bytes, it should match the `input` number  
+Two-way testing can be implemented in the test-runner:
+- Encoding: After encoding the given input number `value`, the output should match `ssz`
+- Decoding: After decoding the given `ssz` bytes, it should match the input number `value` 
 
 ## Forks
 
 Forks-interpretation: `collective` 
-
-```
-
-```

test_generators/ssz/uint_test_cases.py

@@ -15,7 +15,7 @@ from renderers import (
 random.seed(0)
 
 
-BIT_SIZES = [i for i in range(8, 512 + 1, 8)]
+BIT_SIZES = [8, 16, 32, 64, 128, 256]
 RANDOM_TEST_CASES_PER_BIT_SIZE = 10
 RANDOM_TEST_CASES_PER_LENGTH = 3