[pranesh-sridhar]

Add unit tests to cover code paths in nine core packages that the existing suites did not exercise. Gaps were identified from measured nyc coverage of each package's dist/ output. Only test files are changed (plus model-api-builder's package.json and tsconfig.json to wire up the test script and devDependencies, as no tests existed there at all).

Coverage summary

Package	Tests before	Tests after	Statements before	Statements after
model-api-builder	0	5	0% (no test script)	100%
http-caching-proxy	13	22	93.84%	98.46% (branches 55% → 94%)
openapi-spec-builder	27	50	88.60%	100% statements/branches/functions/lines
rest-crud	19	26	68.23%	100% statements/lines
filter	212	216	96.83%	99.36% (branches 87% → 97%)
repository-json-schema	161	165	95.48%	98.87%
repository (types)	—	+7	object.ts 68%, buffer.ts 95% br	both 100%
rest	—	+16	redirect-route 71% stmts	100% stmts/lines
tsdocs	4	7	86.39%	88.43% (helper.ts unscoped branch covered)

Tests added

• model-api-builder: asModelApiBuilder binding template (extensionFor tag, namespace tag, tagNames, key unchanged), MODEL_API_BUILDER_PLUGINS constant
• http-caching-proxy: constructor guard, stop() no-op when not running, logError() with logError:true/false, error.stack present/absent branches; integration test for non-ENOENT cache corruption (EINTEGRITY) falling back to backend
• openapi-spec-builder: withOperationReturningString with and without operationName, withOperation accepting an OperationSpecBuilder, withComponents accepting a ComponentsSpecBuilder, withComponents idempotency (??=), withRequestBody, withStringResponse default status, setupOperationId not overwriting an existing id, all nine ComponentsSpecBuilder methods called twice to hit the ??= already-initialised branch
• rest-crud: CrudRestComponent registers binding; CrudRestApiBuilder.build() — missing basePath error, non-Entity model error, creates repo+controller when absent, reuses existing repo binding, registers readonly controller
• filter: WhereBuilder.impose and FilterBuilder.impose with falsy internal state (defensive !this.where/!this.filter branches that are unreachable via the public API but reachable via direct property mutation)
• repository-json-schema: getNavigationalPropertyForRelation with targetsMany:false (returns targetRef) and targetsMany:true (returns array); getJsonSchema with includeRelations:true on a belongsTo relation (covers the keyFrom foreign-key branch); model with two indexed properties (covers the indexInfo merge path)
• repository: BufferType.coerce with explicit encoding options (covers the options ?? {} non-null branch); ObjectType.coerce for already-correct-type instance, primitive, array; ObjectType.serialize with toJSON, without toJSON, and null/undefined
• rest: RedirectRoute.isRedirectRoute — true, false (no targetLocation), false (wrong description), null, undefined; describe(), updateBindings() no-op, invokeHandler() calls response.redirect; RoutingTable.find throws NotFound without external routes; InfoSpecEnhancer.modifySpec — null pkg skip, override-info path, keep-existing path; parseAuthor with string, object, and null author
• tsdocs: getUnscopedPackageName with unscoped name (no @ prefix); runExtractorForPackage with silent:false (covers the console.log('> %s', pkg.name) branch)

Only test files are changed; there are no source changes.

Checklist

• DCO (Developer Certificate of Origin) signed in all commits
• npm test passes on your machine (ran each affected package's build and tests; lint-staged ran Prettier + ESLint clean on all changed files; full monorepo npm test not run)
• New tests added or existing tests modified to cover all changes
• Code conforms with the style guide
• API Documentation in code was updated (n/a, tests only)
• Documentation in /docs/site was updated (n/a)
• Affected artifact templates in packages/cli were updated (n/a)
• Affected example projects in examples/* were updated (n/a)