Address Analyzer Warnings (#2078)

* Address potential errors

* Add tests

* Add clarity

* Run formatting

test/Api.Test/Models/Request/Accounts/PremiumRequestModelTests.cs

@@ -0,0 +1,70 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using Bit.Api.Models.Request.Accounts;
+using Bit.Core.Settings;
+using Microsoft.AspNetCore.Http;
+using Xunit;
+
+namespace Bit.Api.Test.Models.Request.Accounts
+{
+    public class PremiumRequestModelTests
+    {
+        public static IEnumerable<object[]> GetValidateData()
+        {
+            // 1. selfHosted
+            // 2. formFile
+            // 3. country
+            // 4. expected
+
+            yield return new object[] { true, null, null, false };
+            yield return new object[] { true, null, "US", false };
+            yield return new object[] { true, new NotImplementedFormFile(), null, false };
+            yield return new object[] { true, new NotImplementedFormFile(), "US", false };
+
+            yield return new object[] { false, null, null, false };
+            yield return new object[] { false, null, "US", true }; // Only true, cloud with null license AND a Country
+            yield return new object[] { false, new NotImplementedFormFile(), null, false };
+            yield return new object[] { false, new NotImplementedFormFile(), "US", false };
+        }
+
+        [Theory]
+        [MemberData(nameof(GetValidateData))]
+        public void Validate_Success(bool selfHosted, IFormFile formFile, string country, bool expected)
+        {
+            var gs = new GlobalSettings
+            {
+                SelfHosted = selfHosted
+            };
+
+            var sut = new PremiumRequestModel
+            {
+                License = formFile,
+                Country = country,
+            };
+
+            Assert.Equal(expected, sut.Validate(gs));
+        }
+    }
+
+    public class NotImplementedFormFile : IFormFile
+    {
+        public string ContentType => throw new NotImplementedException();
+
+        public string ContentDisposition => throw new NotImplementedException();
+
+        public IHeaderDictionary Headers => throw new NotImplementedException();
+
+        public long Length => throw new NotImplementedException();
+
+        public string Name => throw new NotImplementedException();
+
+        public string FileName => throw new NotImplementedException();
+
+        public void CopyTo(Stream target) => throw new NotImplementedException();
+        public Task CopyToAsync(Stream target, CancellationToken cancellationToken = default) => throw new NotImplementedException();
+        public Stream OpenReadStream() => throw new NotImplementedException();
+    }
+}