From 708207305cf4de9bb31d15b78a4f837a36cd87d7 Mon Sep 17 00:00:00 2001
From: Oliver Booth <me@olivr.me>
Date: Fri, 31 Mar 2023 20:15:59 +0100
Subject: [PATCH] test: use fixed point of reference for Age tests

---
 X10D.Tests/src/Time/DateTimeOffsetTests.cs | 34 ++++++++++++++++++----
 X10D.Tests/src/Time/DateTimeTests.cs       | 34 ++++++++++++++++++----
 2 files changed, 58 insertions(+), 10 deletions(-)

diff --git a/X10D.Tests/src/Time/DateTimeOffsetTests.cs b/X10D.Tests/src/Time/DateTimeOffsetTests.cs
index eb2d937..cfc364e 100644
--- a/X10D.Tests/src/Time/DateTimeOffsetTests.cs
+++ b/X10D.Tests/src/Time/DateTimeOffsetTests.cs
@@ -1,4 +1,4 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 using X10D.Time;
 
 namespace X10D.Tests.Time;
@@ -7,12 +7,36 @@ namespace X10D.Tests.Time;
 public class DateTimeOffsetTests
 {
     [TestMethod]
-    public void Age_ShouldBeDifference_Given1Jan2000()
+    public void Age_ShouldBe17_Given31December1991Birthday_And30December2017Date()
     {
-        DateTimeOffset birthday = new DateTime(2000, 1, 1);
-        DateTimeOffset today = DateTime.Now.Date;
+        var reference = new DateTime(2017, 12, 30);
+        DateTimeOffset birthday = new DateTime(1999, 12, 31);
 
-        Assert.AreEqual(today.Year - birthday.Year, birthday.Age());
+        int age = birthday.Age(reference);
+
+        Assert.AreEqual(17, age);
+    }
+
+    [TestMethod]
+    public void Age_ShouldBe18_Given31December1991Birthday_And1January2018Date()
+    {
+        var reference = new DateTime(2018, 1, 1);
+        DateTimeOffset birthday = new DateTime(1999, 12, 31);
+
+        int age = birthday.Age(reference);
+
+        Assert.AreEqual(18, age);
+    }
+
+    [TestMethod]
+    public void Age_ShouldBe18_Given31December1991Birthday_And31December2017Date()
+    {
+        var reference = new DateTime(2017, 12, 31);
+        DateTimeOffset birthday = new DateTime(1999, 12, 31);
+
+        int age = birthday.Age(reference);
+
+        Assert.AreEqual(18, age);
     }
 
     [TestMethod]
diff --git a/X10D.Tests/src/Time/DateTimeTests.cs b/X10D.Tests/src/Time/DateTimeTests.cs
index d08b78e..7fc9f50 100644
--- a/X10D.Tests/src/Time/DateTimeTests.cs
+++ b/X10D.Tests/src/Time/DateTimeTests.cs
@@ -1,4 +1,4 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 using X10D.Time;
 
 namespace X10D.Tests.Time;
@@ -7,12 +7,36 @@ namespace X10D.Tests.Time;
 public class DateTimeTests
 {
     [TestMethod]
-    public void Age_ShouldBeDifference_Given1Jan2000()
+    public void Age_ShouldBe17_Given31December1991Birthday_And30December2017Date()
     {
-        var birthday = new DateTime(2000, 1, 1);
-        DateTime today = DateTime.Now.Date;
+        var reference = new DateTime(2017, 12, 30);
+        var birthday = new DateTime(1999, 12, 31);
 
-        Assert.AreEqual(today.Year - birthday.Year, birthday.Age());
+        int age = birthday.Age(reference);
+
+        Assert.AreEqual(17, age);
+    }
+
+    [TestMethod]
+    public void Age_ShouldBe18_Given31December1991Birthday_And1January2018Date()
+    {
+        var reference = new DateTime(2018, 1, 1);
+        var birthday = new DateTime(1999, 12, 31);
+
+        int age = birthday.Age(reference);
+
+        Assert.AreEqual(18, age);
+    }
+
+    [TestMethod]
+    public void Age_ShouldBe18_Given31December1991Birthday_And31December2017Date()
+    {
+        var reference = new DateTime(2017, 12, 31);
+        var birthday = new DateTime(1999, 12, 31);
+
+        int age = birthday.Age(reference);
+
+        Assert.AreEqual(18, age);
     }
 
     [TestMethod]