From 4c1330dd0cea3a32eafc0f9c9d49e4c0f941d44d Mon Sep 17 00:00:00 2001
From: killij <51908793+killij@users.noreply.github.com>
Date: Fri, 8 Dec 2023 15:52:35 +0000
Subject: [PATCH] fix: Azure throws an Exception when the index doesn't exist

Why do companies do this? Just imagine if SQL Server threw an exception every time a query didn't return any results. Not finding something IS NOT EXCEPTIONAL.
---
 ...ndexerTest.cs => ResourcesIndexerTests.cs} | 41 +++++++++++++++----
 .../Core/ResourcesIndexer.cs                  | 29 ++++++++++---
 2 files changed, 58 insertions(+), 12 deletions(-)
 rename src/Childrens-Social-Care-CPD-Indexer.Tests/Core/{ResourcesIndexerTest.cs => ResourcesIndexerTests.cs} (79%)

diff --git a/src/Childrens-Social-Care-CPD-Indexer.Tests/Core/ResourcesIndexerTest.cs b/src/Childrens-Social-Care-CPD-Indexer.Tests/Core/ResourcesIndexerTests.cs
similarity index 79%
rename from src/Childrens-Social-Care-CPD-Indexer.Tests/Core/ResourcesIndexerTest.cs
rename to src/Childrens-Social-Care-CPD-Indexer.Tests/Core/ResourcesIndexerTests.cs
index fd27f3e..199e241 100644
--- a/src/Childrens-Social-Care-CPD-Indexer.Tests/Core/ResourcesIndexerTest.cs
+++ b/src/Childrens-Social-Care-CPD-Indexer.Tests/Core/ResourcesIndexerTests.cs
@@ -1,13 +1,42 @@
 using Azure;
+using Azure.Core;
 using Azure.Search.Documents;
 using Azure.Search.Documents.Indexes;
 using Azure.Search.Documents.Indexes.Models;
 using Childrens_Social_Care_CPD_Indexer.Core;
 using Microsoft.Extensions.Logging;
+using NSubstitute.ExceptionExtensions;
+using System.Diagnostics.CodeAnalysis;
 
 namespace Childrens_Social_Care_CPD_Indexer.Tests.Core;
 
-public class ResourcesIndexerTest
+internal sealed class MockResponse : Response
+{
+    public override int Status => 404;
+    public override string ReasonPhrase => string.Empty;
+
+    public override Stream? ContentStream
+    {
+        get => new MemoryStream();
+        set => throw new NotImplementedException();
+    }
+    public override string ClientRequestId
+    {
+        get => throw new NotImplementedException();
+        set => throw new NotImplementedException();
+    }
+
+    public override void Dispose() => throw new NotImplementedException();
+    protected override bool ContainsHeader(string name) => false;
+    protected override IEnumerable<HttpHeader> EnumerateHeaders() => Array.Empty<HttpHeader>();
+    protected override bool TryGetHeader(string name, [NotNullWhen(true)] out string? value) {
+        value = null;
+        return false;
+    }
+    protected override bool TryGetHeaderValues(string name, [NotNullWhen(true)] out IEnumerable<string>? values) => throw new NotImplementedException();
+}
+
+public class ResourcesIndexerTests
 {
     private ILogger _logger;
     private SearchIndexClient _client;
@@ -28,9 +57,8 @@ public void Setup()
     public async Task DeleteIndexAsync_Skips_Deletion_If_Index_Does_Not_Exist()
     {
         // arrange
-        var response = Substitute.For<Response<SearchIndex>>();
-        response.HasValue.Returns(false);
-        _client.GetIndexAsync(Arg.Any<string>(), Arg.Any<CancellationToken>()).Returns(Task.FromResult(response));
+        var exception = new RequestFailedException(new MockResponse());
+        _client.GetIndexAsync(Arg.Any<string>(), Arg.Any<CancellationToken>()).Throws(exception);
 
         // act
         await _sut.DeleteIndexAsync("foo");
@@ -77,9 +105,8 @@ public async Task DeleteIndexAsync_Logs_Failure_To_Delete_Index()
     public async Task CreateIndexAsync_Creates_The_Index()
     {
         // arrange
-        var getIndexResult = Substitute.For<Response<SearchIndex>>();
-        getIndexResult.HasValue.Returns(false);
-        _client.GetIndexAsync(Arg.Any<string>(), Arg.Any<CancellationToken>()).Returns(Task.FromResult(getIndexResult));
+        var exception = new RequestFailedException(new MockResponse());
+        _client.GetIndexAsync(Arg.Any<string>(), Arg.Any<CancellationToken>()).Throws(exception);
 
         SearchIndex? searchIndex = null;
         await _client.CreateIndexAsync(Arg.Do<SearchIndex>(x => searchIndex = x), Arg.Any<CancellationToken>());
diff --git a/src/Childrens-Social-Care-CPD-Indexer/Core/ResourcesIndexer.cs b/src/Childrens-Social-Care-CPD-Indexer/Core/ResourcesIndexer.cs
index 1c3124d..d8e6841 100644
--- a/src/Childrens-Social-Care-CPD-Indexer/Core/ResourcesIndexer.cs
+++ b/src/Childrens-Social-Care-CPD-Indexer/Core/ResourcesIndexer.cs
@@ -1,14 +1,33 @@
-using Azure.Search.Documents.Indexes;
+using Azure;
+using Azure.Search.Documents.Indexes;
 using Azure.Search.Documents.Indexes.Models;
 
 namespace Childrens_Social_Care_CPD_Indexer.Core;
 
 internal class ResourcesIndexer(SearchIndexClient searchIndexClient, IDocumentFetcher documentFetcher, ILogger logger): IResourcesIndexer
 {
+    private async Task<bool> IndexExistsAsync(string indexName, CancellationToken cancellationToken)
+    {
+        try
+        {
+            var index = await searchIndexClient.GetIndexAsync(indexName, cancellationToken);
+            return index.HasValue;
+        }
+        catch (RequestFailedException rf)
+        {
+            if (rf.Status == 404)
+            {
+                return false;
+            }
+
+            throw;
+        }
+    }
+
     public async Task CreateIndexAsync(string indexName, CancellationToken cancellationToken = default)
     {
-        var index = await searchIndexClient.GetIndexAsync(indexName, cancellationToken);
-        if (index.HasValue)
+        var indexExists = await IndexExistsAsync(indexName, cancellationToken);
+        if (indexExists)
         {
             logger.LogInformation("Index already exists, skipping creation.");
             return;
@@ -25,8 +44,8 @@ public async Task CreateIndexAsync(string indexName, CancellationToken cancellat
     public async Task DeleteIndexAsync(string indexName, CancellationToken cancellationToken = default)
     {
         logger.LogInformation("Deleting index...");
-        var index = await searchIndexClient.GetIndexAsync(indexName, cancellationToken);
-        if (index.HasValue)
+        var indexExists = await IndexExistsAsync(indexName, cancellationToken);
+        if (indexExists)
         {
             var deleteResponse = await searchIndexClient.DeleteIndexAsync(indexName, cancellationToken);
             if (deleteResponse.IsError)