test: add e2e and unit tests for the invalid account check

Signed-off-by: dosi <dosi.kolev@limechain.tech>

Author: Dosik13

sdk/mirror_node_account_balance_query_e2e_test.go

@@ -189,15 +189,16 @@ func TestIntegrationMirrorNodeAccountBalanceQueryCanGetContractBalance(t *testin
 	require.NoError(t, err)
 }
 
-func TestIntegrationMirrorNodeAccountBalanceQueryNonExistentAccountIsZero(t *testing.T) {
+func TestIntegrationMirrorNodeAccountBalanceQueryNonExistentAccountErrors(t *testing.T) {
 	t.Parallel()
 	env := NewIntegrationTestEnv(t)
 	defer CloseIntegrationTestEnv(env, nil)
 
-	balance, err := NewMirrorNodeAccountBalanceQuery().
+	_, err := NewMirrorNodeAccountBalanceQuery().
 		SetAccountID(AccountID{Account: 999999999}).
 		Execute(env.Client)
 
-	require.NoError(t, err, "an unknown account is an empty balances array, not an error")
-	assert.Zero(t, balance.Hbars.AsTinybar())
+	var status ErrHederaPreCheckStatus
+	require.ErrorAs(t, err, &status)
+	assert.Equal(t, StatusInvalidAccountID, status.Status)
 }

sdk/mirror_node_account_balance_query_unit_test.go

@@ -5,6 +5,7 @@ package hiero
 // SPDX-License-Identifier: Apache-2.0
 
 import (
+	"errors"
 	"fmt"
 	"net/http"
 	"net/url"
@@ -131,17 +132,49 @@ func TestUnitMirrorNodeAccountBalanceQueryResolvesContractID(t *testing.T) {
 	assert.Equal(t, "0.0.98765", gotAccountID)
 }
 
-func TestUnitMirrorNodeAccountBalanceQueryNonExistentAccountIsZero(t *testing.T) {
+// An empty list must not read as a zero balance: the caller could not tell a missing account from
+// one holding nothing. It maps onto the status AccountBalanceQuery reported for the same case.
+func TestUnitMirrorNodeAccountBalanceQueryNonExistentAccountErrors(t *testing.T) {
 	var gotAccountID string
 	client := newMockMirrorClient(t, "missing.example.com:443", balancesHandler(t, &gotAccountID,
 		`{"timestamp":null,"balances":[],"links":{"next":null}}`))
 
-	balance, err := NewMirrorNodeAccountBalanceQuery().
+	_, err := NewMirrorNodeAccountBalanceQuery().
 		SetAccountID(AccountID{Account: 999999999}).
 		Execute(client)
 
-	require.NoError(t, err, "an empty balances array is a zero balance, not an error")
-	assert.Equal(t, HbarFromTinybar(0), balance.Hbars)
+	var status ErrHederaPreCheckStatus
+	require.ErrorAs(t, err, &status)
+	assert.Equal(t, StatusInvalidAccountID, status.Status)
+	assert.Contains(t, err.Error(), "INVALID_ACCOUNT_ID")
+}
+
+func TestUnitMirrorNodeAccountBalanceQueryZeroBalanceIsNotMissing(t *testing.T) {
+	var gotAccountID string
+	client := newMockMirrorClient(t, "zerobalance.example.com:443", balancesHandler(t, &gotAccountID,
+		`{"balances":[{"account":"0.0.42","balance":0}]}`))
+
+	balance, err := NewMirrorNodeAccountBalanceQuery().
+		SetAccountID(AccountID{Account: 42}).
+		Execute(client)
+
+	require.NoError(t, err)
+	assert.Zero(t, balance.Hbars.AsTinybar())
+}
+
+func TestUnitMirrorNodeAccountBalanceQueryMissingBalancesArrayIsMalformed(t *testing.T) {
+	var gotAccountID string
+	client := newMockMirrorClient(t, "nobalances.example.com:443", balancesHandler(t, &gotAccountID,
+		`{"timestamp":null,"links":{"next":null}}`))
+
+	_, err := NewMirrorNodeAccountBalanceQuery().
+		SetAccountID(AccountID{Account: 7}).
+		Execute(client)
+
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "no balances array")
+	var status ErrHederaPreCheckStatus
+	assert.False(t, errors.As(err, &status), "a malformed payload must not read as a missing account")
 }
 
 func TestUnitMirrorNodeAccountBalanceQueryNoAccountIDErrorsBeforeRequest(t *testing.T) {