From d3804774d4a3c06b83bbdd4737c840a58a0021ed Mon Sep 17 00:00:00 2001
From: Dev Ojha <ValarDragon@users.noreply.github.com>
Date: Wed, 2 Jan 2019 13:14:12 -0600
Subject: [PATCH] Fix is_valid bug (#3211)

---
 types/coin.go      |  6 ++----
 types/coin_test.go | 10 ++++++++--
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/types/coin.go b/types/coin.go
index e569674026..55a479748f 100644
--- a/types/coin.go
+++ b/types/coin.go
@@ -140,10 +140,8 @@ func (coins Coins) IsValid() bool {
 	case 1:
 		return coins[0].IsPositive()
 	default:
-		if strings.ToLower(coins[0].Denom) != coins[0].Denom {
-			return false
-		}
-		if !coins[0].IsPositive() {
+		// Check single coin case
+		if !(Coins{coins[0]}).IsValid() {
 			return false
 		}
 		lowDenom := coins[0].Denom
diff --git a/types/coin_test.go b/types/coin_test.go
index 92036adfca..851d155155 100644
--- a/types/coin_test.go
+++ b/types/coin_test.go
@@ -251,8 +251,13 @@ func TestMinusCoins(t *testing.T) {
 
 func TestCoins(t *testing.T) {
 	good := Coins{
-		{"GAS", NewInt(1)},
-		{"MINERAL", NewInt(1)},
+		{"gas", NewInt(1)},
+		{"mineral", NewInt(1)},
+		{"tree", NewInt(1)},
+	}
+	mixedCase1 := Coins{
+		{"gAs", NewInt(1)},
+		{"MineraL", NewInt(1)},
 		{"TREE", NewInt(1)},
 	}
 	empty := Coins{
@@ -287,6 +292,7 @@ func TestCoins(t *testing.T) {
 	}
 
 	assert.True(t, good.IsValid(), "Coins are valid")
+	assert.False(t, mixedCase1.IsValid(), "Coins denoms contain upper case characters")
 	assert.True(t, good.IsPositive(), "Expected coins to be positive: %v", good)
 	assert.False(t, null.IsPositive(), "Expected coins to not be positive: %v", null)
 	assert.True(t, good.IsAllGTE(empty), "Expected %v to be >= %v", good, empty)