ACP2E-707 Credit memo Refund Shipping (Incl. Tax) shows -0.01

Author: Chhandak.Barua

app/code/Magento/Sales/Model/Order/Creditmemo/Total/Shipping.php

@@ -61,7 +61,7 @@ public function collect(\Magento\Sales\Model\Order\Creditmemo $creditmemo)
         $baseAllowedAmountInclTaxDiff = $orderBaseShippingInclTax
             - $order->getBaseShippingRefunded()
             - $order->getBaseShippingTaxRefunded();
-        $baseAllowedAmountInclTax = ($baseAllowedAmountInclTaxDiff > 0) ? $baseAllowedAmountInclTaxDiff : 0;
+        $baseAllowedAmountInclTax = $this->getBaseAllowedAmountInclTax($baseAllowedAmountInclTaxDiff);
         // Check if the desired shipping amount to refund was specified (from invoice or another source).
         if ($creditmemo->hasBaseShippingAmount()) {
             // For the conditional logic, we will either use amounts that always include tax -OR- never include tax.
@@ -142,4 +142,15 @@ private function getTaxConfig()
         }
         return $this->taxConfig;
     }
+
+    /**
+     * Get base allowed amount including Tax.
+     *
+     * @return float
+     *
+     */
+    private function getBaseAllowedAmountInclTax($baseAllowedAmountInclTaxDiff)
+    {
+        return ($baseAllowedAmountInclTaxDiff > 0) ? $baseAllowedAmountInclTaxDiff : 0;
+    }
 }

app/code/Magento/Sales/Test/Unit/Model/Order/Creditmemo/Total/ShippingTest.php

@@ -405,4 +405,88 @@ public function testCollectUsingTaxInclShippingAmount()
 
         $this->shippingCollector->collect($this->creditmemoMock);
     }
+    /**
+     * situation: The admin user did *not* specify any desired refund amount
+     *
+     * @throws LocalizedException
+     */
+    public function testCollectRefundShippingAmountIncTax()
+    {
+        $orderShippingAmount = 7.2300;
+        $orderShippingRefunded = 7.2300;
+        $allowedShippingAmount = $orderShippingAmount - $orderShippingRefunded;
+        $baseOrderShippingAmount = 7.9500;
+        $baseOrderShippingRefunded = 7.2300;
+        $baseAllowedShippingAmount = $baseOrderShippingAmount - $baseOrderShippingRefunded;
+        $shippingTaxAmount = 0;
+        $shippingTaxAmountRefunded = 7.9500;
+        $baseShippingTaxAmount = 0;
+        $baseShippingTaxAmountRefunded = 0.7300;
+
+        $expectedShippingAmountInclTax = $allowedShippingAmount + $shippingTaxAmount - $shippingTaxAmountRefunded;
+        $expectedBaseShippingAmountInclTax =
+            $baseAllowedShippingAmount + $baseShippingTaxAmount - $baseShippingTaxAmountRefunded;
+        $grandTotalBefore = 14.35;
+        $baseGrandTotalBefore = 14.35;
+        $expectedGrandTotal = $grandTotalBefore + $allowedShippingAmount;
+        $expectedBaseGrandTotal = $baseGrandTotalBefore + $baseAllowedShippingAmount;
+
+        $this->taxConfig->expects($this->any())->method('displaySalesShippingInclTax')->willReturn(false);
+
+        $order = new DataObject(
+            [
+                'shipping_amount' => $orderShippingAmount,
+                'shipping_refunded' => $orderShippingRefunded,
+                'base_shipping_amount' => $baseOrderShippingAmount,
+                'base_shipping_refunded' => $baseOrderShippingRefunded,
+                'shipping_incl_tax' => $orderShippingAmount + $shippingTaxAmount,
+                'base_shipping_incl_tax' => $baseOrderShippingAmount + $baseShippingTaxAmount,
+                'shipping_tax_amount' => $shippingTaxAmount,
+                'shipping_tax_refunded' => $shippingTaxAmountRefunded,
+                'base_shipping_tax_amount' => $baseShippingTaxAmount,
+                'base_shipping_tax_refunded' => $baseShippingTaxAmountRefunded,
+            ]
+        );
+
+        $this->creditmemoMock->expects($this->once())
+            ->method('getOrder')
+            ->willReturn($order);
+        $this->creditmemoMock->expects($this->once())
+            ->method('hasBaseShippingAmount')
+            ->willReturn(false);
+        $this->creditmemoMock->expects($this->once())
+            ->method('getGrandTotal')
+            ->willReturn($grandTotalBefore);
+        $this->creditmemoMock->expects($this->once())
+            ->method('getBaseGrandTotal')
+            ->willReturn($baseGrandTotalBefore);
+
+        //verify
+        $this->creditmemoMock->expects($this->once())
+            ->method('setShippingAmount')
+            ->with($allowedShippingAmount)
+            ->willReturnSelf();
+        $this->creditmemoMock->expects($this->once())
+            ->method('setBaseShippingAmount')
+            ->with($baseAllowedShippingAmount)
+            ->willReturnSelf();
+        $this->creditmemoMock->expects($this->once())
+            ->method('setShippingInclTax')
+            ->with($expectedShippingAmountInclTax)
+            ->willReturnSelf();
+        $this->creditmemoMock->expects($this->once())
+            ->method('setBaseShippingInclTax')
+            ->with($this->shippingCollector->getBaseAllowedAmountInclTax($expectedBaseShippingAmountInclTax))
+            ->willReturnSelf();
+        $this->creditmemoMock->expects($this->once())
+            ->method('setGrandTotal')
+            ->with($expectedGrandTotal)
+            ->willReturnSelf();
+        $this->creditmemoMock->expects($this->once())
+            ->method('setBaseGrandTotal')
+            ->with($expectedBaseGrandTotal)
+            ->willReturnSelf();
+        $this->assertEquals(0, $this->shippingCollector->getBaseAllowedAmountInclTax($expectedBaseShippingAmountInclTax));
+        $this->shippingCollector->collect($this->creditmemoMock);
+    }
 }