Happy flow for creating realms works

But needs more validating...

IdentityShroud.Core.Tests/Services/EncryptionServiceTests.cs

@@ -0,0 +1,22 @@
+using System.Security.Cryptography;
+using IdentityShroud.Core.Services;
+
+namespace IdentityShroud.Core.Tests.Services;
+
+public class EncryptionServiceTests
+{
+    [Fact]
+    public void RoundtripWorks()
+    {
+        // setup
+        string key = Convert.ToBase64String(RandomNumberGenerator.GetBytes(32));
+        EncryptionService sut = new(key);
+        byte[] input = RandomNumberGenerator.GetBytes(16);
+        
+        // act
+        var cipher = sut.Encrypt(input);
+        var result = sut.Decrypt(cipher);
+
+        Assert.Equal(input, result);
+    }
+}

IdentityShroud.Core.Tests/Services/RealmServiceTests.cs

@@ -0,0 +1,52 @@
+using FluentResults;
+using IdentityShroud.Core.Services;
+using IdentityShroud.Core.Tests.Fixtures;
+using IdentityShroud.Core.Tests.Substitutes;
+using Microsoft.EntityFrameworkCore;
+
+namespace IdentityShroud.Core.Tests.Services;
+
+public class RealmServiceTests : IClassFixture<DbFixture>
+{
+    private readonly Db _db;
+
+    public RealmServiceTests(DbFixture dbFixture)
+    {
+        _db = dbFixture.CreateDbContext("realmservice");
+
+        if (!_db.Database.EnsureCreated())
+            TruncateTables();
+    }
+
+    private void TruncateTables()
+    {
+        _db.Database.ExecuteSqlRaw("TRUNCATE realm CASCADE;");
+    }
+
+    [Theory]
+    [InlineData(null)]
+    [InlineData("a7c2a39c-3ed9-4790-826e-43bb2e5e480c")]
+    public async Task Create(string? idString)
+    {
+        Guid? realmId = null;
+        if (idString is not null)
+            realmId = new(idString);
+        
+        var encryptionService = EncryptionServiceSubstitute.CreatePassthrough();
+        RealmService sut = new(_db, encryptionService);
+        
+        var response = await sut.Create(
+            new(realmId, "slug", "New realm"),
+            TestContext.Current.CancellationToken);
+        
+        RealmCreateResponse val = ResultAssert.Success(response);
+        if (realmId.HasValue)
+            Assert.Equal(realmId, val.Realm.Id);
+        else
+            Assert.NotEqual(Guid.Empty, val.Realm.Id);
+        
+        Assert.Equal("slug", val.Realm.Slug);
+        Assert.Equal("New realm", val.Realm.Name);
+        Assert.NotEmpty(val.Realm.PrivateKeyEncrypted);
+    }
+}