[test-improver] Improve tests for mcp schema package

[github-actions]

Test Improvements: schema_test.go

File Analyzed

• New Test File: internal/mcp/schema_test.go
• Package: internal/mcp
• Implementation: internal/mcp/schema.go — NormalizeInputSchema function

Why This File Was Selected

internal/mcp/schema.go contained the NormalizeInputSchema function with 8 distinct code branches but had no unit test file in the mcp package itself. The only tests were integration-style tests in internal/server/schema_normalization_test.go (a different package), which means:

• Running go test -cover ./internal/mcp/... would show 0% coverage for schema.go
• Tests were far from the code they exercise
• Several branches and edge cases were untested (field preservation in copies, immutability guarantees, non-string type values, toolName variants)

Improvements Made

1. Direct Unit Test Coverage in the Correct Package

• ✅ Created internal/mcp/schema_test.go in the mcp package for direct coverage
• ✅ Uses testify assert for clean, idiomatic assertions
• ✅ Table-driven tests with clear name fields for all branch cases

2. Complete Branch Coverage

All 8 branches of NormalizeInputSchema are now exercised with direct unit tests:

Branch	Description
nil schema	Returns default empty object schema
Empty schema {}	No type, no properties → empty object schema
No type, has properties	Adds "type": "object" via copy
Non-string type value	Returned as-is
Non-"object" type string	Returned as-is ("string", "array", etc.)
Object with properties	Returned as-is
Object with only additionalProperties	Returned as-is
Object missing both	Adds "properties": {} via copy

3. New Edge Cases Not Covered Elsewhere

• ✅ Field preservation: "required", "description" survive copy-producing branches
• ✅ Immutability: original schema not mutated for any branch that creates a copy
• ✅ Reference isolation: returned map is a distinct reference from the original
• ✅ toolName variants: empty string, special chars, long names — all normalized identically
• ✅ Deeply nested schemas: returned as-is without modification

4. Cleaner Test Structure

• Standalone TestNormalizeInputSchema_NilSchema for the most fundamental case
• TestNormalizeInputSchema_AllBranches for the complete table-driven set
• Focused sub-tests for immutability and field preservation concerns

Test Structure

TestNormalizeInputSchema_NilSchema
TestNormalizeInputSchema_AllBranches
  - empty schema returns default empty object schema
  - schema without type but with properties adds object type
  - string type schema returned as-is
  - array type schema returned as-is
  - non-string type value returned as-is
  - object schema with properties returned as-is
  - object schema with only additionalProperties returned as-is
  - object schema with properties and additionalProperties returned as-is
  - object type without properties gets empty properties added
TestNormalizeInputSchema_PreservesExtraFields
  - no-type schema with properties preserves required and description
  - object schema without properties preserves required and description
TestNormalizeInputSchema_DoesNotMutateOriginal
  - nil schema does not panic and returns new map
  - no-type schema with properties is not mutated
  - object schema without properties is not mutated
  - returned map is a different reference than original for mutating branches
TestNormalizeInputSchema_ToolNameVariants
  - (6 tool name variants)
TestNormalizeInputSchema_DeepNestedSchema

Coverage Impact

Package	Before	After
internal/mcp (schema.go)	0% direct	100% direct

The server-package integration tests remain unchanged and continue to provide cross-package validation.

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[Copilot]

Pull request overview

Adds direct unit-test coverage for internal/mcp.NormalizeInputSchema, complementing existing integration-style coverage in internal/server and ensuring go test -cover ./internal/mcp/... exercises schema.go.

Changes:

• Introduces internal/mcp/schema_test.go with table-driven tests covering all normalization branches.
• Adds focused tests for field preservation and non-mutation guarantees in copy-producing branches.
• Exercises toolName input variants and a deeply nested schema “no-op” case.

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