[Isabelle (ibrandes)]

This PR unblocks my netty 100 continue support PR by fixing the flaky/failing proxy tests causing CI failures. (Note: the CI failures began on October 7th before my netty 100 continue support PR)

Link to pipeline example failure

Summary

NettyAsyncHttpClientBuilderTests.buildWithEnvConfigurationProxy (and, latently, buildWithExplicitConfigurationProxy) read the real proxy environment of the CI agent, so they fail deterministically on hosted agents that sit behind a proxy. This PR makes proxy resolution in these tests self-contained by shadowing the ambient HTTP_PROXY/HTTPS_PROXY/NO_PROXY so the tests depend only on their own TestConfigurationSource values.

Root cause

com.azure.core.implementation.util.EnvironmentConfiguration.getOrLoad falls back to the real System.getenv(name) / System.getProperty(name) for any key a test ConfigurationSource leaves unset. The env-style test cases set only HTTP_PROXY, so HTTPS_PROXY and NO_PROXY fell through to the agent's real values. ProxyOptions.fromConfiguration reads HTTPS_PROXY before HTTP_PROXY and also reads NO_PROXY, which on hosted Windows agents (HTTPS_PROXY=http://10.x.x.x:18080, NO_PROXY=localhost,127.0.0.1,…) produced:

• localhost targets bypassed by the real NO_PROXY → no proxy handler (expected: not <null>), and
• authenticated external targets picking up the credential-less real HTTPS_PROXY → netty's plain HttpProxyHandler instead of Azure's (expected <true> but was <false>).

The buildWithExplicitConfigurationProxy supplier used the global-environment new ConfigurationBuilder(), so it had the same latent exposure.

Changes

Test-only, in sdk/core/azure-core-http-netty/.../NettyAsyncHttpClientBuilderTests.java:

• Added a shared NEUTRAL_PROXY_ENV_SOURCE that sets HTTP_PROXY/HTTPS_PROXY/NO_PROXY to "", and used it as the environment source for every ConfigurationBuilder in both proxy-test suppliers (replacing EMPTY_SOURCE / the global new ConfigurationBuilder()).
• For the two env-style cases that carry their proxy config in the environment slot (simpleEnvProxy, envProxyWithAuthentication), explicitly shadowed HTTPS_PROXY/NO_PROXY.

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[Copilot]

🟡 Changes recommended

Ambient JVM proxy properties can still leak into the tests and alter proxy selection.

1 open finding

• Isolate tests from unrelated JVM proxy system properties · New

What changed in this PR

Isolates Netty proxy tests from ambient CI proxy environment variables.

Changes:

• Adds a neutral proxy environment source.
• Applies it across environment and explicit proxy test configurations.

File	Description
NettyAsyncHttpClientBuilderTests.java	Shadows ambient proxy environment variables in proxy tests.

🧠 Review effort: Balanced

[Copilot]

🔵 Needs a closer look

Two environment-proxy cases remain vulnerable to an ambient java.net.useSystemProxies JVM property.

0 open findings

1 resolved since last review

• Isolate tests from unrelated JVM proxy system properties

🧠 Review effort: Balanced

[Copilot]

🟢 Approval recommended

The focused test-only changes consistently prevent ambient proxy settings from affecting the tested scenarios.

0 open findings

🧠 Review effort: Balanced

[Isabelle (ibrandes)]

Issue was fixed after upgrading to Netty 4.2