types/Header: ambiguous comment about Hash() returning nil if "required" fields are missing #723
Description
So currently in
Lines 172 to 188 in 7682ad9
The comment says:
// NOTE: hash is nil if required fields are missing.
But that's a bit unclear/over-generalized. Perhaps later on we should improve that doc to say it returns nil if ValidatorsHash is nil because I'd have thought not including other fields would also cause it to fail.
package test_it
import (
"testing"
"github.com/google/gofuzz"
"github.com/tendermint/tendermint/types"
)
func TestFuzzMerkleHash(t *testing.T) {
f := fuzz.New()
n := 100000
nonNilCount := uint64(0)
for i := 0; i < n; i++ {
hdr := new(types.Header)
f.Fuzz(hdr)
hash := hdr.Hash()
if hash != nil {
nonNilCount += 1
}
}
t.Logf("nonNilCount: %d/%d", nonNilCount, n)
}Shooting at it with a fuzzer reveals that most times "randomly" folks can get it right 80% with guesses so that comment perhaps needs an update
Emmanuels-MacBook-Pro-2:types emmanuelodeke$ go test -v -run=FuzzMerkle
=== RUN TestFuzzMerkleHash
--- PASS: TestFuzzMerkleHash (3.47s)
hdr_test.go:595: nonNilCount: 80128/100000
Emmanuels-MacBook-Pro-2:types emmanuelodeke$ go test -v -run=FuzzMerkle
=== RUN TestFuzzMerkleHash
--- PASS: TestFuzzMerkleHash (3.55s)
hdr_test.go:595: nonNilCount: 80131/100000
Emmanuels-MacBook-Pro-2:types emmanuelodeke$ go test -v -run=FuzzMerkle
=== RUN TestFuzzMerkleHash
--- PASS: TestFuzzMerkleHash (3.63s)
hdr_test.go:595: nonNilCount: 80074/100000
Emmanuels-MacBook-Pro-2:types emmanuelodeke$ go test -v -run=FuzzMerkle
=== RUN TestFuzzMerkleHash
--- PASS: TestFuzzMerkleHash (4.08s)
hdr_test.go:595: nonNilCount: 80426/100000
Emmanuels-MacBook-Pro-2:types emmanuelodeke$ go test -v -run=FuzzMerkle
=== RUN TestFuzzMerkleHash
--- PASS: TestFuzzMerkleHash (3.59s)
hdr_test.go:595: nonNilCount: 80017/100000