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Fix Cosmos' QueryItems silently parsing non-success responses as data #2836

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Merged
vcolin7 merged 2 commits into from
Jun 9, 2026
Merged

Fix Cosmos' QueryItems silently parsing non-success responses as data #2836

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9e2cc33
Fix Cosmos QueryItems silently parsing non-success responses as data
vcolin7 Jun 5, 2026
91f087f
Potential fix for pull request finding
vcolin7 Jun 9, 2026
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3 changes: 3 additions & 0 deletions servers/Azure.Mcp.Server/changelog-entries/1780624204134.yaml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
changes:
- section: "Bugs Fixed"
description: "Fixed an issue where the Cosmos DB QueryItems operation silently parsed non-success (e.g. throttled or auth-failure) responses as data. The response is now validated before parsing so failures surface as errors."
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2 changes: 2 additions & 0 deletions tools/Azure.Mcp.Tools.Cosmos/src/Services/CosmosService.cs
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Expand Up @@ -288,6 +288,8 @@ public async Task<List<JsonElement>> QueryItems(
while (queryIterator.HasMoreResults)
{
using ResponseMessage response = await queryIterator.ReadNextAsync(cancellationToken);
response.EnsureSuccessStatusCode();

using var document = JsonDocument.Parse(response.Content);
items.Add(document.RootElement.Clone());
}
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25 changes: 25 additions & 0 deletions tools/Azure.Mcp.Tools.Cosmos/tests/Azure.Mcp.Tools.Cosmos.Tests/CosmosServiceTests.cs
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Expand Up @@ -195,6 +195,31 @@ await _cacheService.DidNotReceive().GetAsync<CosmosClient>(
Arg.Any<CancellationToken>());
}

[Fact]
public async Task QueryItems_NonSuccessResponse_Throws()
{
// Arrange: route the CosmosClient's transport through the mocked IHttpClientFactory so it always returns 403.
var handler = new MockHttpHandler(HttpStatusCode.Forbidden);
_httpClientFactory.CreateClient(Arg.Any<string>()).Returns(new HttpClient(handler));
var clientOptions = new CosmosClientOptions { HttpClientFactory = () => _httpClientFactory.CreateClient() };

var credential = Substitute.For<TokenCredential>();
var token = new AccessToken("fake-token", DateTimeOffset.UtcNow.AddHours(1));
credential.GetTokenAsync(Arg.Any<TokenRequestContext>(), Arg.Any<CancellationToken>())
.Returns(new ValueTask<AccessToken>(token));
credential.GetToken(Arg.Any<TokenRequestContext>(), Arg.Any<CancellationToken>())
.Returns(token);

using var cosmosClient = new CosmosClient("https://myaccount.documents.azure.com", credential, clientOptions);

_cacheService.GetAsync<CosmosClient>(Arg.Any<string>(), Arg.Any<string>(), Arg.Any<TimeSpan?>(), Arg.Any<CancellationToken>())
.Returns(cosmosClient);

// Act & Assert: a non-success response must throw rather than being returned as a data item
await Assert.ThrowsAnyAsync<CosmosException>(() =>
_service.QueryItems("myaccount", "mydb", "mycontainer", "SELECT * FROM c", "sub123", AuthMethod.Key, cancellationToken: TestContext.Current.CancellationToken));
}

private sealed class MockHttpHandler(HttpStatusCode statusCode) : HttpMessageHandler
{
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
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