Require the latest 6.x before upgrading to 7

The RavenDB 6.2 to 7.2 data upgrade is one-way, and the 6.x data
migrations must finish on RavenDB 6.2 first. Add 6.21.0 as the last
version of major 6 to the upgrade path, as 5.11.0 was added for the move
to 6. Instances on an older version are told to upgrade to 6.21.0 first.

Author: danielmarbach

src/ServiceControlInstaller.Engine.UnitTests/Configuration/UpgradeInfoTests.cs

@@ -0,0 +1,56 @@
+namespace ServiceControlInstaller.Engine.UnitTests.Configuration
+{
+    using NuGet.Versioning;
+    using NUnit.Framework;
+    using ServiceControlInstaller.Engine.Configuration.ServiceControl;
+
+    [TestFixture]
+    public class UpgradeInfoTests
+    {
+        [TestCase("6.21.0")]
+        [TestCase("6.21.0-beta.1")]
+        [TestCase("6.21.2")]
+        [TestCase("6.22.0")]
+        [TestCase("7.0.0")]
+        public void Should_accept_the_latest_version_of_major_6_and_later(string current)
+        {
+            var upgradeInfo = UpgradeInfo.GetUpgradePathFor(SemanticVersion.Parse(current));
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(upgradeInfo.HasIncompatibleVersion, Is.False);
+                Assert.That(upgradeInfo.UpgradePath, Is.Empty);
+            });
+        }
+
+        [TestCase("6.0.0", "6.21.0")]
+        [TestCase("6.20.0", "6.21.0")]
+        public void Should_require_the_latest_version_of_major_6_from_an_older_6(string current, string expectedPath)
+        {
+            var upgradeInfo = UpgradeInfo.GetUpgradePathFor(SemanticVersion.Parse(current));
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(upgradeInfo.HasIncompatibleVersion, Is.True);
+                Assert.That(upgradeInfo.ToString(), Is.EqualTo(expectedPath));
+            });
+        }
+
+        [TestCase("5.11.0", "6.21.0")]
+        [TestCase("5.11.11", "6.21.0")]
+        [TestCase("5.0.0", "5.11.0 ➡️ 6.21.0")]
+        [TestCase("4.33.0", "5.11.0 ➡️ 6.21.0")]
+        [TestCase("4.26.0", "4.33.0 ➡️ 5.11.0 ➡️ 6.21.0")]
+        [TestCase("1.0.0", "1.48.0 ➡️ 2.1.5 ➡️ 3.8.4 ➡️ 4.33.0 ➡️ 5.11.0 ➡️ 6.21.0")]
+        public void Should_keep_requiring_the_last_version_of_each_earlier_major(string current, string expectedPath)
+        {
+            var upgradeInfo = UpgradeInfo.GetUpgradePathFor(SemanticVersion.Parse(current));
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(upgradeInfo.HasIncompatibleVersion, Is.True);
+                Assert.That(upgradeInfo.ToString(), Is.EqualTo(expectedPath));
+            });
+        }
+    }
+}

src/ServiceControlInstaller.Engine/Configuration/ServiceControl/UpgradeInfo.cs

@@ -11,7 +11,8 @@ public class UpgradeInfo
             new(2, 1, 5),
             new(3, 8, 4),
             new(4, 33, 0), // Added IngestErrorMessages setting to enable message replay during 4to5 upgrade guide scenario 
-            new(5, 11, 0)
+            new(5, 11, 0),
+            new(6, 21, 0)
         ];
 
         public SemanticVersion[] UpgradePath { get; private init; }