[code-simplifier] simplify: use indexer-style dict initializer and inline lambdas in SerializerUtilities

[Evangelink]

Code Simplification — 2026-06-10

This PR simplifies recently modified code from #8974 (SerializerUtilities refactoring) to improve clarity, consistency, and alignment with project coding standards.

Files Simplified

• src/Platform/Microsoft.Testing.Platform/ServerMode/JsonRpc/SerializerUtilities.cs — fix dictionary initializer coding standard violation, eliminate local variable
• src/Platform/Microsoft.Testing.Platform/ServerMode/JsonRpc/SerializerUtilities.TestNodeSerializers.cs — standardize two lambdas to match the expression-body pattern used by other serializers in the same file

Improvements Made

1. Fix Add-style dictionary initializer (coding standard violation)

SerializerUtilities.cs contained the only Add-style { { key, value } } dictionary initializer across the four serializer files. The project coding standards explicitly require the indexer syntax [key] = value for dictionary initializers. Replaced and removed the unnecessary local variable:

// Before
Serializers[typeof(KeyValuePair<string, string>)] = new ObjectSerializer<KeyValuePair<string, string>>(o =>
{
    Dictionary<string, object?> values = new()
    {
        { o.Key, o.Value },
    };
    return values;
});

// After
Serializers[typeof(KeyValuePair<string, string>)] = new ObjectSerializer<KeyValuePair<string, string>>(
    o => new Dictionary<string, object?> { [o.Key] = o.Value });

2. Standardize verbose lambdas in SerializerUtilities.TestNodeSerializers.cs

TestNodeUpdateMessage and TestNodeStateChangedEventArgs serializers used a verbose block-body pattern with a local values variable and an explicit return, while Artifact and RunResponseArgs in the same file already used the cleaner expression-body pattern. Aligned them:

// Before
Serializers[typeof(TestNodeUpdateMessage)] = new ObjectSerializer<TestNodeUpdateMessage>(ev =>
{
    Dictionary<string, object?> values = new()
    {
        [JsonRpcStrings.Node] = Serialize(ev.TestNode),
        [JsonRpcStrings.Parent] = ev.ParentTestNodeUid?.Value,
    };
    return values;
});

// After
Serializers[typeof(TestNodeUpdateMessage)] = new ObjectSerializer<TestNodeUpdateMessage>(ev => new Dictionary<string, object?>
{
    [JsonRpcStrings.Node] = Serialize(ev.TestNode),
    [JsonRpcStrings.Parent] = ev.ParentTestNodeUid?.Value,
});

Changes Based On

Recent changes from:

• Refactor SerializerUtilities.cs into focused partial class files #8974 — Refactor SerializerUtilities.cs into focused partial class files (merged 2026-06-10)

Testing

• ✅ No functional changes — behavior is identical
• ✅ The KeyValuePair<string, string> serializer still produces { key: value } (indexer setter has same semantics as Add for non-duplicate keys)
• ✅ Both lambdas produce the same Dictionary<string, object?> as before

Review Focus

Please verify:

• Functionality is preserved (indexer vs Add produces same result for non-duplicate keys)
• Simplifications improve consistency within the files
• Changes align with project conventions (indexer-style dict initializers, expression-body lambdas)

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Pull request overview

This PR performs small, non-functional simplifications in the JSON-RPC serialization utilities within Microsoft.Testing.Platform, aligning serializer lambdas and dictionary initializers with established repo coding standards and patterns used elsewhere in the same serializer set.

Changes:

• Replaced an Add-style dictionary initializer with an indexer-style initializer for the KeyValuePair<string, string> serializer and inlined the dictionary creation.
• Simplified the TestNodeUpdateMessage and TestNodeStateChangedEventArgs serializers to use expression-bodied lambdas consistent with other serializers in the same file.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Platform/ServerMode/JsonRpc/SerializerUtilities.cs	Uses indexer-style dictionary initializer for the KeyValuePair<string,string> serializer and removes the temporary local variable.
src/Platform/Microsoft.Testing.Platform/ServerMode/JsonRpc/SerializerUtilities.TestNodeSerializers.cs	Inlines dictionary creation in two serializer lambdas to match the expression-bodied pattern used by nearby serializers.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 0

[Evangelink]

Note

🤖 Automated review by GitHub Copilot. Posted via a maintainer's GitHub token, so it appears under their account — the account owner did not write or approve this content personally. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

✅ 22/22 dimensions clean — no findings.

Scope: src/Platform/Microsoft.Testing.Platform/ServerMode/JsonRpc/ (serialization hot-path — hotspot dimensions Threading, Performance, IPC Wire Compatibility applied with extra scrutiny.)

Notes per applicable dimension:

• Algorithmic Correctness — Behavior is preserved. The { { o.Key, o.Value } } Add-style initializer and { [o.Key] = o.Value } indexer initializer both produce an identical single-entry dictionary for a KeyValuePair<string, string> (the only consumer being test-metadata trait serialization). No edge case difference surfaces.
• IPC Wire Compatibility — The serialized key/value pairs are unchanged in all three lambdas. No wire format regression.
• Performance — No allocation delta; local variable elimination is neutral to the JIT.
• Cross-TFM — Indexer-style collection initializers and expression-body lambdas compile identically across net462, netstandard2.0, net8.0, and net9.0.
• Code Structure & Simplification — Changes align the two converted lambdas with the expression-body pattern already used by every other serializer in the same file (Artifact, DiscoverResponseArgs, RunResponseArgs). Consistent style throughout the file is a net positive.
• Coding Standards Compliance — Both transformations follow the explicit project guideline: "prefer the indexer syntax [key] = value over the Add-style { { key, value } } initializer"; and "ensure the final return statement of a method is on its own line" is satisfied by eliminating the intermediary local variable entirely.
• Test Completeness — Purely mechanical style change; no behavioral path altered, so no new tests are required.
• Dimensions 2 (Threading), 3 (Security), 4 (Public API), 7 (IDisposable), 8 (Defensive Coding), 9 (Localization), 10–14 (Test dimensions), 17 (Documentation), 18 (Analyzer Quality), 20 (Build Infrastructure), 22 (PowerShell) — all N/A for this diff.

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