feat: foo20 check an error from grc20 package (#977)

examples/gno.land/r/demo/foo20/foo20.gno

@@ -49,17 +49,26 @@ func Allowance(owner, spender users.AddressOrName) uint64 {
 
 func Transfer(to users.AddressOrName, amount uint64) {
 	caller := std.PrevRealm().Addr()
-	foo.Transfer(caller, to.Resolve(), amount)
+	err := foo.Transfer(caller, to.Resolve(), amount)
+	if err != nil {
+		panic(err)
+	}
 }
 
 func Approve(spender users.AddressOrName, amount uint64) {
 	caller := std.PrevRealm().Addr()
-	foo.Approve(caller, spender.Resolve(), amount)
+	err := foo.Approve(caller, spender.Resolve(), amount)
+	if err != nil {
+		panic(err)
+	}
 }
 
 func TransferFrom(from, to users.AddressOrName, amount uint64) {
 	caller := std.PrevRealm().Addr()
-	foo.TransferFrom(caller, from.Resolve(), to.Resolve(), amount)
+	err := foo.TransferFrom(caller, from.Resolve(), to.Resolve(), amount)
+	if err != nil {
+		panic(err)
+	}
 }
 
 // faucet.
@@ -68,21 +77,30 @@ func Faucet() {
 	// FIXME: add limits?
 	// FIXME: add payment in gnot?
 	caller := std.PrevRealm().Addr()
-	foo.Mint(caller, 1000*10000) // 1k
+	err := foo.Mint(caller, 1000*10000) // 1k
+	if err != nil {
+		panic(err)
+	}
 }
 
 // administration.
 
 func Mint(address users.AddressOrName, amount uint64) {
 	caller := std.PrevRealm().Addr()
 	assertIsAdmin(caller)
-	foo.Mint(address.Resolve(), amount)
+	err := foo.Mint(address.Resolve(), amount)
+	if err != nil {
+		panic(err)
+	}
 }
 
 func Burn(address users.AddressOrName, amount uint64) {
 	caller := std.PrevRealm().Addr()
 	assertIsAdmin(caller)
-	foo.Burn(address.Resolve(), amount)
+	err := foo.Burn(address.Resolve(), amount)
+	if err != nil {
+		panic(err)
+	}
 }
 
 // render.

examples/gno.land/r/demo/foo20/foo20_test.gno

@@ -54,3 +54,39 @@ func TestReadOnlyPublicMethods(t *testing.T) {
 		}
 	}
 }
+
+func TestErrConditions(t *testing.T) {
+	admin := std.Address("g1us8428u2a5satrlxzagqqa5m6vmuze025anjlj")
+	empty := std.Address("")
+
+	type test struct {
+		name string
+		msg  string
+		fn   func()
+	}
+
+	std.TestSetOrigCaller(admin)
+	{
+		tests := []test{
+			{"Transfer(admin, 1)", "cannot send transfer to self", func() { Transfer(users.AddressOrName(admin), 1) }},
+			{"Approve(empty, 1))", "invalid address", func() { Approve(users.AddressOrName(empty), 1) }},
+		}
+		for _, tc := range tests {
+			shouldPanicWithMsg(t, tc.fn, tc.msg)
+		}
+	}
+}
+
+func shouldPanicWithMsg(t *testing.T, f func(), msg string) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Errorf("The code did not panic")
+		} else {
+			errMsg := error(r).Error()
+			if errMsg != msg {
+				t.Errorf("excepted panic(%v), got(%v)", msg, errMsg)
+			}
+		}
+	}()
+	f()
+}