From 2900872f322e3437167fa8fd6fcd53ac0f45fbe4 Mon Sep 17 00:00:00 2001
From: Duncan McClean <duncan@duncanmcclean.com>
Date: Wed, 21 Jun 2023 19:35:50 +0100
Subject: [PATCH] Rollback tax calculation fix from the other day

---
 src/Tax/Standard/TaxEngine.php      |  8 ++++----
 tests/Tax/StandardTaxEngineTest.php | 20 ++++++++++----------
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/src/Tax/Standard/TaxEngine.php b/src/Tax/Standard/TaxEngine.php
index e487ce26d..2d8f2759c 100644
--- a/src/Tax/Standard/TaxEngine.php
+++ b/src/Tax/Standard/TaxEngine.php
@@ -38,8 +38,8 @@ public function calculateForLineItem(Order $order, LineItem $lineItem): TaxCalcu
             }
         }
 
-        $taxAmount = $lineItem->total() * ($taxRate->rate() / 100);
-        $itemTax = (int) round($taxAmount);
+        $taxAmount = ($lineItem->total() / 100) * ($taxRate->rate() / (100 + $taxRate->rate()));
+        $itemTax = (int) round($taxAmount * 100);
 
         return new TaxCalculation($itemTax, $taxRate->rate(), $taxRate->includeInPrice());
     }
@@ -111,8 +111,8 @@ public function calculateForShipping(Order $order, ShippingMethod $shippingMetho
             }
         }
 
-        $taxAmount = $order->shippingTotal() * ($taxRate->rate() / 100);
-        $itemTax = (int) round($taxAmount);
+        $taxAmount = ($order->shippingTotal() / 100) * ($taxRate->rate() / (100 + $taxRate->rate()));
+        $itemTax = (int) round($taxAmount * 100);
 
         return new TaxCalculation($itemTax, $taxRate->rate(), $taxRate->includeInPrice());
     }
diff --git a/tests/Tax/StandardTaxEngineTest.php b/tests/Tax/StandardTaxEngineTest.php
index d5f37c6f8..c7bd008dc 100644
--- a/tests/Tax/StandardTaxEngineTest.php
+++ b/tests/Tax/StandardTaxEngineTest.php
@@ -93,13 +93,13 @@
 
     // Ensure tax on line items are right
     $this->assertSame($recalculate->lineItems()->first()->tax(), [
-        'amount' => 200,
+        'amount' => 167,
         'rate' => 20,
         'price_includes_tax' => false,
     ]);
 
     // Ensure global order tax is right
-    expect(200)->toBe($recalculate->taxTotal());
+    expect(167)->toBe($recalculate->taxTotal());
 });
 
 test('can correctly calculate line item tax rate based on region', function () {
@@ -162,13 +162,13 @@
 
     // Ensure tax on line items are right
     $this->assertSame($recalculate->lineItems()->first()->tax(), [
-        'amount' => 150,
+        'amount' => 130,
         'rate' => 15,
         'price_includes_tax' => false,
     ]);
 
     // Ensure global order tax is right
-    expect(150)->toBe($recalculate->taxTotal());
+    expect(130)->toBe($recalculate->taxTotal());
 });
 
 test('can calculate line item tax rate when included in price', function () {
@@ -229,13 +229,13 @@
 
     // Ensure tax on line items are right
     $this->assertSame($recalculate->lineItems()->first()->tax(), [
-        'amount' => 200,
+        'amount' => 167,
         'rate' => 20,
         'price_includes_tax' => true,
     ]);
 
     // Ensure global order tax is right
-    expect(200)->toBe($recalculate->taxTotal());
+    expect(167)->toBe($recalculate->taxTotal());
 });
 
 test('can use default line item tax rate if no rate available', function () {
@@ -289,7 +289,7 @@
     expect(12)->toBe($recalculate->lineItems()->first()->tax()['rate']);
 
     // Ensure global order tax is right
-    expect(120)->toBe($recalculate->taxTotal());
+    expect(107)->toBe($recalculate->taxTotal());
 });
 
 test('throws prevent checkout exception if no rate available', function () {
@@ -400,7 +400,7 @@
     expect(99)->toBe($recalculate->lineItems()->first()->tax()['rate']);
 
     // Ensure global order tax is right
-    expect(990)->toBe($recalculate->taxTotal());
+    expect(497)->toBe($recalculate->taxTotal());
 });
 
 test('throws prevent checkout exception if no address provided', function () {
@@ -525,8 +525,8 @@
     $recalculate = $order->recalculate();
 
     // Ensure 10% is deducted from shipping_total (500 -> 450)
-    expect($recalculate->shippingTotal())->toBe(450);
+    expect($recalculate->shippingTotal())->toBe(455);
 
     // Ensure tax total is 50
-    expect($recalculate->taxTotal())->toBe(50);
+    expect($recalculate->taxTotal())->toBe(45);
 });