Tests: Add unit tests for untested modules

[evans-sam]

Problem

Several core modules have no dedicated test file and are covered only incidentally via integration tests in client-test.js:

• src/http.ts (346 LOC)
• src/utils.ts (266 LOC)
• src/nscontext.ts (232 LOC)
• src/soap.ts (100 LOC)
• src/types.ts (144 LOC — type-only, maybe N/A)

Why it matters

Integration tests catch happy paths. Edge cases (malformed namespaces, unusual HTTP response shapes, utility boundary conditions) usually fall through the cracks. Once coverage (#4) is in place this gap will show up quantitatively.

Proposed approach

For each module, add a test/<module>-test.js exercising:

• Every exported function.
• Edge cases not naturally hit by client tests (empty input, nulls, malformed shapes).
• Error paths.

Skip types.ts if it's purely interface declarations.

Acceptance criteria

• Each non-type module has a dedicated test file.
• Coverage for these modules visibly improves in the coverage report (Bump body-parser from 2.2.0 to 2.2.2 #4).