types: allow genesis file to have 0 validators (#2148)

* fixing issue 2015

* Remove comments for code review

* Update tests

.gitignore

@@ -37,3 +37,5 @@ addrbook.json
 terraform.tfstate
 terraform.tfstate.backup
 terraform.tfstate.d
+
+.vscode

types/genesis.go

@@ -25,7 +25,7 @@ type GenesisDoc struct {
 	GenesisTime     time.Time          `json:"genesis_time"`
 	ChainID         string             `json:"chain_id"`
 	ConsensusParams *ConsensusParams   `json:"consensus_params,omitempty"`
-	Validators      []GenesisValidator `json:"validators"`
+	Validators      []GenesisValidator `json:"validators,omitempty"`
 	AppHash         cmn.HexBytes       `json:"app_hash"`
 	AppState        json.RawMessage    `json:"app_state,omitempty"`
 }
@@ -65,10 +65,6 @@ func (genDoc *GenesisDoc) ValidateAndComplete() error {
 		}
 	}
 
-	if len(genDoc.Validators) == 0 {
-		return cmn.NewError("The genesis file must have at least one validator")
-	}
-
 	for _, v := range genDoc.Validators {
 		if v.Power == 0 {
 			return cmn.NewError("The genesis file cannot contain validators with no voting power: %v", v)

types/genesis_test.go

@@ -14,15 +14,14 @@ import (
 func TestGenesisBad(t *testing.T) {
 	// test some bad ones from raw json
 	testCases := [][]byte{
-		[]byte{},                                           // empty
-		[]byte{1, 1, 1, 1, 1},                              // junk
-		[]byte(`{}`),                                       // empty
-		[]byte(`{"chain_id":"mychain"}`),                   // missing validators
-		[]byte(`{"chain_id":"mychain","validators":[]}`),   // missing validators
-		[]byte(`{"chain_id":"mychain","validators":[{}]}`), // missing validators
-		[]byte(`{"chain_id":"mychain","validators":null}`), // missing validators
-		[]byte(`{"chain_id":"mychain"}`),                   // missing validators
-		[]byte(`{"validators":[{"pub_key":{"type":"tendermint/PubKeyEd25519","value":"AT/+aaL1eB0477Mud9JMm8Sh8BIvOYlPGC9KkIUmFaE="},"power":"10","name":""}]}`), // missing chain_id
+		[]byte{},              // empty
+		[]byte{1, 1, 1, 1, 1}, // junk
+		[]byte(`{}`),          // empty
+		[]byte(`{"chain_id":"mychain","validators":[{}]}`), // invalid validator
+		// missing pub_key type
+		[]byte(`{"validators":[{"pub_key":{"value":"AT/+aaL1eB0477Mud9JMm8Sh8BIvOYlPGC9KkIUmFaE="},"power":"10","name":""}]}`),
+		// missing chain_id
+		[]byte(`{"validators":[{"pub_key":{"type":"tendermint/PubKeyEd25519","value":"AT/+aaL1eB0477Mud9JMm8Sh8BIvOYlPGC9KkIUmFaE="},"power":"10","name":""}]}`),
 	}
 
 	for _, testCase := range testCases {
@@ -62,6 +61,19 @@ func TestGenesisGood(t *testing.T) {
 	assert.NoError(t, err, "error marshalling genDoc")
 	genDoc, err = GenesisDocFromJSON(genDocBytes)
 	assert.Error(t, err, "expected error for genDoc json with block size of 0")
+
+	// Genesis doc from raw json
+	missingValidatorsTestCases := [][]byte{
+		[]byte(`{"chain_id":"mychain"}`),                 // missing validators
+		[]byte(`{"chain_id":"mychain","validators":[]}`), // missing validators
+		[]byte(`{"chain_id":"mychain","validators":null}`), // nil validator
+		[]byte(`{"chain_id":"mychain"}`), // missing validators
+	}
+
+	for _, tc := range missingValidatorsTestCases {
+		_, err := GenesisDocFromJSON(tc)
+		assert.NoError(t, err)
+	}
 }
 
 func TestGenesisSaveAs(t *testing.T) {