Using fold instead of reduce function to avoid error on empty sales

.devcontainer/devcontainer.json

@@ -1,31 +1,18 @@
-
 {
-	"name": "Ubuntu",
-
-	"build": {
-        "dockerfile": "Dockerfile"
-    },
-
-	"customizations": {
-		"vscode": {
-			"extensions": [
-				"DavidAnson.vscode-markdownlint",
-				"Dart-Code.dart-code",
-				"EditorConfig.EditorConfig",
+  "name": "Salert Dart",
+  "build": {
+    "dockerfile": "Dockerfile"
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "DavidAnson.vscode-markdownlint",
+        "Dart-Code.dart-code",
+        "EditorConfig.EditorConfig",
         "GitHub.vscode-github-actions",
-				"redhat.vscode-yaml"
-			]
-		}
-	},
-
-	// Features to add to the dev container. More info: https://containers.dev/features.
-	// "features": {},
-
-	// Use 'forwardPorts' to make a list of ports inside the container available locally.
-	// "forwardPorts": [],
-
-	"postCreateCommand": "dart --version"
-
-	// Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
-	// "remoteUser": "root"
+        "redhat.vscode-yaml"
+      ]
+    }
+  },
+	"postCreateCommand": "sh ./.devcontainer/postCreateCommand.sh"
 }

.devcontainer/postCreateCommand.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+echo ""
+dart --version
+
+git config --global --add safe.directory /workspaces/*

CHANGELOG.md

@@ -5,6 +5,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.0.8]
+
+### Fixed
+
+- Using `fold` instead of `reduce` function to avoid error on empty sales.
+
 ## [0.0.7]
 
 ### Added

lib/src/item.dart

@@ -97,7 +97,7 @@ class Item implements Sellable {
   double taxOfCodes(List<String> taxCodes) {
     return taxCodes
         .map((taxCode) => taxOf(taxCode))
-        .reduce((value1, value2) => value1 + value2);
+        .fold(.0, (value1, value2) => value1 + value2);
   }
 
   // Calculates discount amount before taxes.

lib/src/sale.dart

@@ -22,45 +22,45 @@ class Sale implements Sellable {
   double get subtotal {
     return _items
         .map((item) => item.subtotal)
-        .reduce((value1, value2) => value1 + value2);
+        .fold(.0, (value1, value2) => value1 + value2);
   }
 
   /// Calculates subtotal amount including [discount] for given [taxCode] (before taxes).
   @override
   double subtotalOf(String taxCode) {
     return _items
         .map((item) => item.subtotalOf(taxCode))
-        .reduce((value1, value2) => value1 + value2);
+        .fold(.0, (value1, value2) => value1 + value2);
   }
 
   /// Calculates tax amount.
   @override
   double get tax {
-    return _items.map((item) => item.tax).reduce((s1, s2) => s1 + s2);
+    return _items.map((item) => item.tax).fold(.0, (s1, s2) => s1 + s2);
   }
 
   /// Calculates tax amount including [discount] for given [taxCode].
   @override
   double taxOf(String taxCode) {
     return _items
         .map((item) => item.taxOf(taxCode))
-        .reduce((value1, value2) => value1 + value2);
+        .fold(.0, (value1, value2) => value1 + value2);
   }
 
   /// Calculates tax amount including [discount] for given [taxCodes].
   @override
   double taxOfCodes(List<String> taxCodes) {
     return _items
         .map((item) => item.taxOfCodes(taxCodes))
-        .reduce((value1, value2) => value1 + value2);
+        .fold(.0, (value1, value2) => value1 + value2);
   }
 
   // Calculates discount amount before taxes.
   @override
   double get discountAmount {
     return _items
         .map((item) => item.discountAmount)
-        .reduce((value1, value2) => value1 + value2);
+        .fold(.0, (value1, value2) => value1 + value2);
   }
 
   /// Calculates total amount.
@@ -99,10 +99,10 @@ class Sale implements Sellable {
     if (discount?.affectsTotal ?? false) {
       final baseSubtotal = items
           .map((item) => item.subtotal)
-          .reduce((value1, value2) => value1 + value2);
+          .fold(.0, (value1, value2) => value1 + value2);
       final baseTax = items
           .map((item) => item.tax)
-          .reduce((value1, value2) => value1 + value2);
+          .fold(.0, (value1, value2) => value1 + value2);
       final baseTotal = baseSubtotal + baseTax + tip;
       var discountValue = discount!.discountOf(baseTotal);
       final discountedSubtotal = _inverseSubtotalOf(baseTotal - discountValue);

test/sale_test.dart

@@ -244,5 +244,13 @@ void main() {
       expect(sale.discountAmountOfSaleAffectingSubtotal, closeTo(1.3, 0.01));
       expect(sale.total, closeTo(10.0, 0.01));
     });
+
+    test('Empty sale calculation', () {
+      var sale = Sale(items: []);
+      expect(sale.subtotal, .0);
+      expect(sale.tax, .0);
+      expect(sale.discountAmount, .0);
+      expect(sale.total, .0);
+    });
   });
 }