diff --git a/tests/test_gridbot.py b/tests/test_gridbot.py
index f66e3cb..28dad36 100644
--- a/tests/test_gridbot.py
+++ b/tests/test_gridbot.py
@@ -190,6 +190,39 @@ def test_get_value_of_orders(instance: KrakenInfinityGridBot) -> None:
     assert value == 0
 
 
+def test_investment(instance: KrakenInfinityGridBot) -> None:
+    """Test the investment property."""
+    instance.orderbook.get_orders.return_value = [
+        {"price": 50000.0, "volume": 0.1},
+        {"price": 49000.0, "volume": 0.2},
+    ]
+    assert instance.investment == 14800.0
+
+    instance.orderbook.get_orders.return_value = []
+    assert instance.investment == 0.0
+
+
+def test_max_investment_reached(instance: KrakenInfinityGridBot) -> None:
+    """Test the max_investment_reached property."""
+    instance.amount_per_grid = 1000.0
+    instance.fee = 0.01
+    instance.max_investment = 20000.0
+
+    # Case where max investment is not reached
+    instance.orderbook.get_orders.return_value = [
+        {"price": 50000.0, "volume": 0.1},
+        {"price": 49000.0, "volume": 0.2},
+    ]
+    assert not instance.max_investment_reached
+
+    # Case where max investment is reached
+    instance.orderbook.get_orders.return_value = [
+        {"price": 50000.0, "volume": 0.3},
+        {"price": 49000.0, "volume": 0.2},
+    ]
+    assert instance.max_investment_reached
+
+
 # ==============================================================================
 # on_message
 ##
diff --git a/tests/test_order_management.py b/tests/test_order_management.py
index 86b62bd..5e35e72 100644
--- a/tests/test_order_management.py
+++ b/tests/test_order_management.py
@@ -161,6 +161,11 @@ def test_check_pending_txids(
     mock_assign_all_pending_transactions.assert_called_once()
 
 
+# ==============================================================================
+# check_near_buy_orders
+##
+
+
 @mock.patch.object(OrderManager, "handle_cancel_order")
 def test_check_near_buy_orders_cancel(
     mock_handle_cancel_order: mock.Mock,  # noqa: ARG001
@@ -194,9 +199,6 @@ def test_check_near_buy_orders_good_distance(
     strategy.get_active_buy_orders.assert_not_called()
 
 
-# ==============================================================================
-# check_n_open_buy_orders
-##
 @mock.patch.object(OrderManager, "handle_cancel_order")
 def test_check_near_buy_orders_cancel_no_buys(
     mock_handle_cancel_order: mock.Mock,  # noqa: ARG001
@@ -211,6 +213,11 @@ def test_check_near_buy_orders_cancel_no_buys(
     strategy.get_active_buy_orders.assert_not_called()
 
 
+# ==============================================================================
+# check_n_open_buy_orders
+##
+
+
 @mock.patch.object(OrderManager, "handle_arbitrage")
 def test_check_n_open_buy_orders(
     mock_handle_arbitrage: mock.Mock,
@@ -227,6 +234,7 @@ def test_check_n_open_buy_orders(
     strategy.n_open_buy_orders = 5
     # Current investment
     strategy.investment = 1000.0
+    strategy.max_investment_reached = False
     # The currently available quote currency
     strategy.get_balances.return_value = {"quote_available": 10000.0}
     # No pending transactions
@@ -279,6 +287,23 @@ def test_check_n_open_buy_orders(
     assert mock_handle_arbitrage.call_count == 4
 
 
+@mock.patch.object(OrderManager, "handle_arbitrage")
+def test_check_n_open_buy_orders_max_investment_reached(
+    mock_handle_arbitrage: mock.Mock,
+    strategy: mock.Mock,
+) -> None:
+    """
+    Test checking that the function does not place any order if the maximum
+    investment is reached.
+    """
+    strategy.max_investment_reached = True
+
+    # Ensure no API call is made in order to avoid rate-limiting
+    strategy.get_balances.assert_not_called()
+    # Ensure no buy orders are placed
+    mock_handle_arbitrage.assert_not_called()
+
+
 # ==============================================================================
 
 
@@ -435,25 +460,6 @@ def test_handle_arbitrage(
 # ==============================================================================
 # new_buy_order
 ##
-def test_new_buy_order_max_invest_reached(
-    order_manager: OrderManager,
-    strategy: mock.Mock,
-) -> None:
-    """
-    Test placing a new buy order, that exceeds the maximum investment defined.
-    """
-    strategy.get_balances.return_value = {"quote_available": 1000.0}
-    strategy.max_investment = 4999.0
-    strategy.max_invest_reached = False
-    strategy.get_value_of_orders.return_value = 5000.0
-    strategy.trade.create_order.return_value = {"txid": ["txid1"]}
-    strategy.trade.truncate.side_effect = [50000.0, 100.0]  # price, volume
-
-    order_manager.new_buy_order(order_price=50000.0)
-
-    assert strategy.max_invest_reached
-    strategy.trade.create_order.assert_not_called()
-    strategy.pending_txids.add.assert_not_called()
 
 
 def test_new_buy_order(
@@ -463,17 +469,29 @@ def test_new_buy_order(
     """Test placing a new buy order successfully."""
     strategy.get_balances.return_value = {"quote_available": 1000.0}
     strategy.max_investment = 6000.0
+    strategy.max_investment_reached = False
     strategy.get_value_of_orders.return_value = 5000.0
     strategy.trade.create_order.return_value = {"txid": ["txid1"]}
     strategy.trade.truncate.side_effect = [50000.0, 100.0]  # price, volume
 
     order_manager.new_buy_order(order_price=50000.0)
-    assert not strategy.max_invest_reached
     strategy.pending_txids.add.assert_called_once_with("txid1")
     strategy.trade.create_order.assert_called_once()
     strategy.om.assign_order_by_txid.assert_called_once_with("txid1")
 
 
+def test_new_buy_order_max_invest_reached(
+    order_manager: OrderManager,
+    strategy: mock.Mock,
+) -> None:
+    """Test placing a new buy order without sufficient funds."""
+    strategy.max_investment_reached = True
+
+    order_manager.new_buy_order(order_price=50000.0)
+    strategy.trade.create_order.assert_not_called()
+    strategy.pending_txids.add.assert_not_called()
+
+
 def test_new_buy_order_not_enough_funds(
     order_manager: OrderManager,
     strategy: mock.Mock,