[test] Add tests for config.StdinServerConfig.UnmarshalJSON

[github-actions]

Test Coverage Improvement: StdinServerConfig.UnmarshalJSON

Function Analyzed

• Package: internal/config
• Function: StdinServerConfig.UnmarshalJSON
• Previous Coverage: 79.2%
• New Coverage: 91.7%
• Complexity: Medium (multiple branches for JSON parsing, legacy field aliases, and unknown field collection)

Why This Function?

StdinServerConfig.UnmarshalJSON is a custom JSON unmarshaler that handles several complex scenarios: legacy snake_case field aliases (connect_timeout, tool_timeout), collecting unknown fields into AdditionalProperties, and setting the toolTimeoutFieldName tracker. Five branches covering error paths and edge cases were completely untested.

Tests Added

• ✅ Invalid JSON input returns error (first unmarshal error path)
• ✅ connect_timeout with non-integer string value returns error
• ✅ tool_timeout with non-integer string value returns error
• ✅ connect_timeout as float returns error (only integers accepted)
• ✅ tool_timeout as float returns error (only integers accepted)
• ✅ null for connect_timeout decodes to pointer-to-zero (documents actual behavior)
• ✅ Both camelCase and snake_case timeout fields present: camelCase wins
• ✅ Only snake_case tool_timeout sets toolTimeoutFieldName to "tool_timeout"
• ✅ camelCase toolTimeout keeps default toolTimeoutFieldName as "toolTimeout"
• ✅ Unknown fields are collected in AdditionalProperties; known fields are excluded

Coverage Report

Before: 79.2% (UnmarshalJSON)
After:  91.7% (UnmarshalJSON)
Improvement: +12.5%

Test Execution

All 10 new sub-tests pass:

--- PASS: TestStdinServerConfig_UnmarshalJSON_ErrorPaths (0.00s)
    --- PASS: .../invalid_JSON_returns_error
    --- PASS: .../connect_timeout_with_non-integer_value_returns_error
    --- PASS: .../tool_timeout_with_non-integer_value_returns_error
    --- PASS: .../connect_timeout_as_float_returns_error
    --- PASS: .../tool_timeout_as_float_returns_error
    --- PASS: .../connect_timeout_as_null_is_treated_as_zero
    --- PASS: .../both_legacy_timeout_fields_present_simultaneously
    --- PASS: .../only_tool_timeout_snake_case_sets_toolTimeoutFieldName
    --- PASS: .../toolTimeout_camelCase_keeps_default_toolTimeoutFieldName
    --- PASS: .../unknown_fields_are_collected_in_AdditionalProperties

---

Generated by Test Coverage Improver
Next run will target the next most complex under-tested function

Warning

Firewall blocked 8 domains

The following domains were blocked by the firewall during workflow execution:

• go.opentelemetry.io
• go.yaml.in
• golang.org
• google.golang.org
• gopkg.in
• invalidhostthatdoesnotexist12345.com
• proxy.golang.org
• sum.golang.org

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "go.opentelemetry.io"
    - "go.yaml.in"
    - "golang.org"
    - "google.golang.org"
    - "gopkg.in"
    - "invalidhostthatdoesnotexist12345.com"
    - "proxy.golang.org"
    - "sum.golang.org"

See Network Configuration for more information.

Generated by Test Coverage Improver · ● 8.8M · ◷

[Copilot]

Pull request overview

Adds focused unit coverage for StdinServerConfig.UnmarshalJSON, documenting legacy timeout alias handling, error paths, field precedence, and additional-property collection.

Changes:

• Adds subtests for invalid JSON and invalid legacy timeout values.
• Covers snake_case vs camelCase timeout precedence and toolTimeoutField tracking.
• Verifies unknown fields are retained in AdditionalProperties.

Show a summary per file

File	Description
internal/config/config_stdin_unmarshal_coverage_test.go	New unit tests for StdinServerConfig.UnmarshalJSON branches and edge cases.

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• Files reviewed: 1/1 changed files
• Comments generated: 0