feat(appkit): add testing kit by IamGalymzhan · Pull Request #530 · databricks/appkit

IamGalymzhan · 2026-08-11T09:08:17Z

Testing Kit

Made PluginContext telemetry injectable — the one production edit. It now takes an optional { telemetry }, defaulting to the real provider for testing.
Created the @databricks/appkit/testing package — moved the fixtures out of tools/test-helpers.ts into packages/appkit/src/testing/
Added the two headline helpers — createTestPluginContext() (wraps the real PluginContext with fake tool providers) and expectStream(...).toEmit(...).
Shipped it to users + added docs page (docs/development/testing.md), a template example test.
Added new tests for analytics and genie plugins using this kit

The testing kit needs to construct a real PluginContext without a live OpenTelemetry pipeline. Add an optional constructor dependency for the telemetry provider, defaulting to the shared "plugin-context" provider so the production path is unchanged. This is the single production edit required to wrap the real class in tests rather than reimplementing it. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

Wire the testing kit as a published subpath and prove it against the first of the two hand-rolled context stubs (the design gate): - Add ./testing to both exports maps (dev + publishConfig) following the ./type-generator shape, add src/testing/index.ts to the tsdown entry, and declare vitest as an optional peerDependency. Build passes attw + publint; dist/testing/{index,mock-plugin-context,expect-stream,fixtures}.{js,d.ts} are emitted and vitest stays external to the main entry. - Migrate dispatch-tool-call.test.ts: replace (plugin as any).context = { executeTool } with mockPluginContext. executeTool is now the REAL method, so the forwarded toolCallTimeoutMs is asserted through actual signal composition, the on-behalf-of (asUser) path is verified, and a new test proves the forwarded timeout actually aborts a slow toolkit tool end-to-end. This is the primary win from the plan: executeTool's OBO and timeout paths gain real assertions instead of a stub that proved nothing. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

…Context Replace the second and final hand-rolled stub — (plugin as any).context = { addRoute } — with the real PluginContext from mockPluginContext. The kit's route recorder captures raw handlers, so the alias assertion (both /invocations and /responses mount the same handler reference) holds against the real class, where forwardAsyncErrors wrapping would otherwise break reference identity. Both context stubs the plan identified are now migrated. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

- Add docs/docs/development/testing.md covering mockPluginContext(), expectStream(), and the fixture helpers, with a full end-to-end example. Cross-links to local-development, custom-plugins, and execution-context. - Add template/server/example.test.ts: a self-contained, plugin-agnostic example that scaffolded apps ship with — it defines a tiny custom plugin and exercises both mockPluginContext (route recording) and expectStream (ordered event assertions), running with no workspace or network. Ships the kit to users, satisfying the plan's acceptance criteria that a docs page exists and the template carries at least one example test. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

Validation by scaffolding a real app with `databricks apps init` surfaced that the examples called the `analytics()`/`toPlugin()` factory and then treated the result as a plugin instance — but a factory returns a { plugin, config, name } descriptor for createApp to construct, so `.attachContext`/handler methods are absent. Rewrite both the template example test and the docs "Full example" to instantiate the plugin class directly (`new GreeterPlugin({})`), matching how the migrated agents suites use the kit. The scaffolded app's `npm test` and `tsc` both pass against the published `@databricks/appkit/testing` subpath with no workspace or network. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

…pe error Drop `undefined` from the static FakeToolValue union. `resolve()` treats an undefined map entry as "unregistered tool" and throws, so allowing undefined as a declared response made `{ query: undefined }` a confusing runtime error instead of a compile error. A function returning undefined still works for the rare "returns nothing" case. Add a test pinning that a null response is returned as a value, not misread as a missing tool. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

…ting kit The plan's step 5 was to MOVE the fixtures into the package, not copy them. The shipped kit (src/testing/fixtures.ts) duplicated all 15 exports of tools/test-helpers.ts, which would drift over time. Collapse the original into a thin re-export of @databricks/appkit/testing so src/testing is the single source of truth while the 18 existing @tools/test-helpers importers keep working unchanged. The re-exported mockServiceContext is now synchronous; every call site either awaits it (no-op on a non-promise) or reads it through Awaited<ReturnType<...>>, so all suites pass unchanged (full appkit suite: 3117 passed, 1 pre-existing skip). Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

…ing docs Code review follow-ups: - expectStream's parseSSEBody split frames on \n\n, so a spec-compliant SSE stream delimited by \r\n\r\n (from a real server) collapsed into one event. AppKit's own writer uses \n\n so existing tests were unaffected, but expectStream is public API that accepts any Response. Normalize CRLF to LF before splitting; add a CRLF regression test. - Docs: instantiate the plugin CLASS in the attach() snippet (the factory returns a descriptor, not an instance), and note that the cache attach() seeds is a per-process singleton shared by tests within a file. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

github-actions · 2026-08-11T09:11:16Z

📦 Bundle size report

Compared against bundle-size-baseline.json (main).

`@databricks/appkit`

npm tarball (packed): 873 KB (+33 KB) — gzipped download (dist + bin; excludes release-only docs/NOTICE).

dist	raw	gzip
JS (runtime)	892 KB (+23 KB)	312 KB (+8.6 KB)
Type declarations	340 KB (+25 KB)	118 KB (+9.1 KB)
Source maps	1.7 MB (+57 KB)	586 KB (+20 KB)
Other	11 KB	3.7 KB
Total	3.0 MB (+106 KB)	1020 KB (+38 KB)

Per-entry composition (own code — deps external (as shipped))

Entry	Initial (gz)	Lazy (gz)	Total (gz)	node_modules (min)	Own code (min)
`.`	88 KB (+15 B)	2.5 KB	91 KB (+15 B)	external	288 KB (+46 B)
`./beta`	49 KB	457 B	49 KB	external	143 KB
`./testing`	17 KB	0 B	17 KB	external	50 KB
`./type-generator`	21 KB	0 B	21 KB	external	61 KB

Chunks:

Entry	Chunk	Load	Size (gz)
`.`	`index.js`	initial	84 KB
`.`	`utils.js`	initial	4.0 KB
`.`	`remote-tunnel-manager.js`	lazy	2.5 KB
`./beta`	`beta.js`	initial	33 KB
`./beta`	`stream-manager.js`	initial	5.8 KB
`./beta`	`wide-event-emitter.js`	initial	3.2 KB
`./beta`	`databricks.js`	initial	3.0 KB
`./beta`	`configuration.js`	initial	2.1 KB
`./beta`	`service-context.js`	initial	1.3 KB
`./beta`	`client.js`	initial	434 B
`./beta`	`client-options.js`	initial	220 B
`./beta`	`supervisor-api.js`	lazy	192 B
`./beta`	`databricks.js`	lazy	142 B
`./beta`	`index.js`	lazy	123 B
`./testing`	`index.js`	initial	17 KB
`./type-generator`	`index.js`	initial	21 KB

`@databricks/appkit-ui`

npm tarball (packed): 342 KB (-291 B) — gzipped download (dist + bin; excludes release-only docs/NOTICE).

dist	raw	gzip
JS (runtime)	390 KB	130 KB (+1 B)
Type declarations	228 KB	83 KB
Source maps	752 KB (-334 B)	247 KB (-197 B)
CSS	16 KB (-462 B)	3.2 KB (-90 B)
Total	1.4 MB (-796 B)	464 KB (-286 B)

Per-entry composition (consumer bundle — deps bundled, peerDeps external)

Entry	Initial (gz)	Lazy (gz)	Total (gz)	node_modules (min)	Own code (min)
`./js`	5.3 KB	49 KB	55 KB	208 KB	14 KB
`./js/beta`	20 B	0 B	20 B	0 B	0 B
`./react`	432 KB (+127 B)	49 KB	480 KB (+127 B)	1.3 MB	175 KB
`./react/beta`	1.0 KB	0 B	1.0 KB	0 B	1.9 KB

Chunks:

Entry	Chunk	Load	Size (gz)
`./js`	`index.js`	initial	5.2 KB
`./js`	`chunk`	initial	120 B
`./js`	`apache-arrow`	lazy	49 KB
`./js/beta`	`beta.js`	initial	20 B
`./react`	`index.js`	initial	430 KB
`./react`	`tslib`	initial	2.1 KB
`./react`	`apache-arrow`	lazy	49 KB
`./react/beta`	`beta.js`	initial	1.0 KB

github-actions · 2026-08-11T09:15:47Z

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📦 Try this PR's app template

Scaffolds a new app from this PR's SDK build. Run it in any folder (requires the GitHub CLI — gh auth login — and the Databricks CLI):

gh run download 32364946014 -R databricks/appkit -n appkit-template-0.61.1-pr.7a2cd6c-feat-testing-kit-530 -D appkit-pr-530 \
  && unzip -o "appkit-pr-530/appkit-template-0.61.1-pr.7a2cd6c-feat-testing-kit-530.zip" -d "appkit-pr-530" \
  && databricks apps init --template "appkit-pr-530"

The template pins @databricks/appkit and @databricks/appkit-ui to tarballs built from this branch, so the scaffolded app runs against this PR's code.

CI's "Lint & Type Check" job runs `pnpm run check` over the whole repo, so a pre-existing lint error unrelated to this branch failed the build: - remote-tunnel-controller.test.ts had two `afterEach` hooks in one describe (lint/suspicious/noDuplicateTestHooks, error severity). Merge them into one — behavior preserved (env reset + console-spy clear both still run after each test). This file is byte-identical to main; the error predated the branch and only surfaced because CI lints the entire tree. Also drop two dead `biome-ignore lint/suspicious/noExplicitAny` suppressions in the testing kit (fixtures.ts, expect-stream.test.ts): `noExplicitAny` is turned off repo-wide in biome.json, so the comments had no effect (suppressions/unused warnings). The invalid-source test now casts through `unknown as never`. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

@example

Verified and fixed the findings from an independent code review: - #1 (correctness) expectStream dropped the wire `event:` name when the JSON payload carried its own `type` (spread ran after the assignment). Spread the payload first, then set `type = name ?? parsed.type`, so a frame like `event: error` + `data: {"type":"result"}` reports `error`. Regression test added. - #2 (contract) `@databricks/appkit/testing` eagerly loads vitest via fixtures even for `expectStream`, so vitest is a real requirement. Drop the "optional" peerDependenciesMeta and correct the docs sentence. - #6 (OBO fidelity) the fake `asUser` recorded `asUser: true` unconditionally. Enforce the real `Plugin.asUser` token precondition: a request without `x-forwarded-access-token` throws `missingToken` (missing user id throws too), and the resolved `userId` is recorded on each tool call. Tests now assert both directions (well-formed request vs token-less). - #3 (fidelity) attach() now mirrors AppKit core: registerPlugin plus registerToolProvider for real tool providers, without clobbering injected fakes. getPlugins()/getPluginNames()/hasPlugin() behave as in production. - #12 unknown-tool lookup used `tools[name] === undefined`, so a tool named "constructor"/"toString" hit Object.prototype. Use Object.hasOwn. - #5 drop data-less named SSE frames (real clients ignore them). - #7 re-export the PluginContext type from the testing barrel so MockPluginContext.ctx is nameable through the exports map. - #13 correct the docs: mock.telemetry captures the context's executeTool spans, not plugin-level spans (attachContext rebuilds the plugin's own telemetry). - #4 parseSSEResponse now delegates to the same parseSSEBody as expectStream — one parser, no divergence. All 3 analytics.integration call sites still pass. - #8 reformat template/server/example.test.ts with the template's Prettier so a scaffolded app's `npm run format` passes. - #10 fix the package-doc @example (agentsPlugin._handleStream does not exist). - #11 add kit tests that exercise attach() end-to-end (cache seed, isReady, registration, fake-not-clobbered). Build passes attw + publint; full appkit suite 3125 passed / 1 pre-existing skip. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

… dep With vitest declared as a (non-optional) peerDependency, knip recognizes it as used, so the earlier ignoreDependencies entry is unnecessary. This reverts knip.json to its original state. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

A required peerDependency has no per-subpath scope: it applied to the whole @databricks/appkit package, so every production consumer that never imports the testing kit got an unsatisfied peer (npm 7+ auto-installs vitest into their tree; pnpm warns) — a wider blast radius than the eager-import bug it was meant to fix. Follow appkit's own precedent instead: `vite` backs the ./type-generator subpath as a normal `dependency`, installed for everyone but loaded only by importers of that subpath. Do the same for `vitest` and ./testing. vitest is referenced solely by dist/testing/fixtures.js, never by the main/plugin/core entry, so a consumer importing createApp never loads it. Verified end-to-end: scaffolded an app whose own vitest (4.1.9) differs in major from appkit's dependency (3.2.4), forcing a nested second copy. The testing kit's vi.fn()/vi.spyOn() mocks and expect(...).toHaveBeenCalled() assertions work across the two instances (vi spies carry their own call state), and npm install emits no peer-dep warning. Build passes attw + publint. Also fold in the template example's Prettier formatting (template uses Prettier, not Biome) so a scaffolded app's `npm run format` passes. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

The helper builds the REAL PluginContext with faked edges — it does not mock the context — so the name was misleading. Rename to createTestPluginContext (and the MockPluginContext type to TestPluginContext), matching the create*-for-tests convention, and rename the files to test-plugin-context.ts. Pre-merge and unreleased, so no external consumers are affected. Also finish the #13 doc-accuracy fix in the shipped JSDoc (not just the docs page): the telemetry field comment now states it captures the context's spans (executeTool), not plugin-internal spans — attachContext rebuilds the plugin's this.telemetry from the real TelemetryManager. These comments ship in dist/testing/*.d.ts, so IntelliSense previously showed the unqualified claim. Build passes attw + publint; full appkit suite 3125 passed / 1 pre-existing skip. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

Behavior-preserving cleanups in the testing kit: - createMockRequest reuses createMockWorkspaceClient() instead of an inline copy of the same mock client (verified identical). - createMockServiceContext / createMockUserContext / mockServiceContext inline the createMockWorkspaceClient() call into the `||` fallback, so the mock client is built only when the caller did not supply one. - The fake asUser view spreads `...base` and overrides executeAgentTool rather than re-declaring getAgentTools. - expectStream's isSubsequence breaks once the expected sequence is fully matched. No semantic change; typecheck clean and all kit + migrated tests pass. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

- #1 (P1) The docs called vitest a peer dependency, but the manifest ships it under `dependencies` (the decision we landed on, matching how appkit ships `vite` for ./type-generator). Correct the docs to match: appkit installs vitest for you, and it loads only when you import ./testing. Manifest and docs now agree. - #2 (P2) expectStream buffered the source eagerly with no bound, so a non-terminating stream hung until the runner's own timeout. Add an optional `{ timeout }` that fails fast with a clear, kit-specific error; document it and cover both directions with tests. - #3 (P2) The fake asUser replicates asUser's token precondition but not the real dev-mode `DEV_OBO_FALLBACK_KEY` OTel marker (a module-private telemetry detail). Narrow the docs and JSDoc to say so and point users at the recorded asUser/userId fields instead of isDevOboFallback(). Build passes attw + publint; full appkit suite 3141 passed / 1 pre-existing skip. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

Exercise @databricks/appkit/testing against real core plugins to validate it beyond the two agent proof sites and produce usage references: - analytics.kit.test.ts: cross-plugin executeTool via createTestPluginContext — OBO identity (asUser/userId), token-precondition rejection, and per-call timeout abort. Needs only the kit (no workspace/ServiceContext). - genie.kit.test.ts: drives the real _handleSendMessage SSE stream and asserts event order with expectStream(...).toEmit(...). Both add genuinely new coverage (streamed SSE order + OBO dispatch identity were untested). Full appkit suite 3145 passed / 1 pre-existing skip. Developer-experience notes (kit wins + friction, e.g. createMockResponse doesn't compose with expectStream) captured in internal/ for the milestone review. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

pkosiec

Testing kit - review

I tried this kit two ways: read it closely, then used it to write real tests for the analytics and genie plugins. Short version: I'd adopt it. Wrapping the real PluginContext and faking only the edges (telemetry, tool providers, routes) gives you things a hand-rolled { executeTool } stub can't - real timeout composition, the real asUser token check, real route recording. attach() and OBO both worked cleanly in a fresh test.

One gap stood out in real use, and a few smaller things are worth a look. Details are in the inline comments; here's the map:

Biggest lever

The kit tests generators well, but you can't assert a plugin's real SSE route - createMockResponse throws the written bytes away. Fixing this is the single change that makes plugin testing feel complete. (see comment on fixtures.ts)

Worth deciding before wide use

vitest as a plain runtime dependency ships a test framework into every production install. An optional peer avoids that. (see package.json)

Convenience

An obo option on createMockRequest (+ show it in the docs example).
A resetTestCache() so the documented cache advice is actually followable.

Polish

The shipped example test uses an any-cast instead of the documented attach().
Two service-context helpers differ only by a create prefix.
A useServiceContextMock() hook could remove the repeated beforeEach/afterEach block.

pkosiec

Round 2 - the new dogfood tests

Thanks for adding these. Both pass, and the analytics one adds real coverage that was missing (cross-plugin executeTool OBO identity).

Two asks:

Don't keep them as separate *.kit.test.ts files. The testing kit should be the default way to test a plugin, not a parallel track. Fold these into analytics.test.ts / genie.test.ts and drop the .kit split. For genie, that also means merging with the existing (presence-only) SSE test into one ordered assertion on the real event names.
Trim the comments. Both files carry a lot of explanatory narration that reads as slop; a /deslop pass when merging would cut it to what's needed.

Bonus signal: these files independently re-hit round 1 - a hand-rolled capturing response (C1), a re-invented service-context mock (C8), and hand-rolled OBO headers (C3). Two authors needing the same workarounds is the strongest case yet to land those kit ergonomics.

Resolve the eight review comments on the testing kit: - createMockResponse now captures written SSE bytes and exposes sseResponse(); expectStream reads a captured mock response directly, so streaming-route tests no longer need a hand-rolled bridge. - Ship vitest as an optional peer dependency (+ devDependency) instead of a plain runtime dependency, keeping the test framework out of production installs and deduping to the app's own copy. Ignore it in knip. - Add an obo option to createMockRequest so on-behalf-of tests set the forwarded identity headers with one flag. - Add resetTestCache() to clear the shared cache singleton between tests. - Use the documented attach() instead of an any-cast in the agents dispatch tests. - Drop the unused createMockServiceContext/createMockUserContext builders from the public surface; keep the service-context builder internal. - Pin the previously untested edges: the Object.hasOwn tool-lookup guard, the dev-mode asUser branch, and parseSSEBody's non-object data values. - Add useServiceContextMock() to register the mock lifecycle in one line, returning a live accessor. Dogfood the new helpers in the analytics, genie, and serving suites, and document them in the testing guide. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

The testing kit is entirely plugin-scoped (createTestPluginContext, attach(plugin), plugin route/tool/SSE assertions), and the page's own cross-links already pointed into plugins/. Move it next to custom-plugins and fix the relative links. Keep the heading as 'Testing'; the Plugins section supplies the context. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

Address round-2 review: the kit should be the default way to test a plugin, not a parallel '*.kit.test.ts' track. - Fold the three cross-plugin executeTool OBO tests into analytics.test.ts and delete analytics.kit.test.ts. - Upgrade genie.test.ts's SSE test to assert event ORDER via expectStream on genie's real event names (message_start, status, message_result, query_result), replacing brittle write.mock.calls substring checks, and delete genie.kit.test.ts. - Trim the heavy comment narration from the folded-in tests. - Re-export createTestPluginContext and expectStream from the test-helpers shim. - Finish the testing-guide move under plugins/ (sidebar position + links). Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

The dogfood fold trimmed expect(mock.toolCalls).toHaveLength(1), so a double-dispatch would no longer fail the happy-path test — and it was inconsistent with the token-less sibling that kept toHaveLength(0). Restore it. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

The toEmit swap pinned event order but dropped the payload values the old substring checks covered (conversationId=new-conv-id, status=ASKING_AI), which aren't asserted elsewhere. Restore them structurally via collect() + toMatchObject — keeping the ordering guarantee without brittle substrings. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

…equest createMockRequest returned userWorkspaceClient, serviceWorkspaceClient, getWarehouseId and getWorkspaceId — fields no production code reads (plugins resolve those through getWorkspaceClient()/getWarehouseId() from src/context, which mockServiceContext stands in for). Publishing them via @databricks/appkit/testing would make four inert fields a permanent public promise. The two warehouse cold-start tests (analytics + metric) overrode mockReq.serviceWorkspaceClient.warehouses.get, which the route never reads — so they passed on the default RUNNING client without exercising the warehouse path at all. Route the warehouse client through mockServiceContext (the real seam) so the tests are live, and drop the 'mock WorkspaceClient' claim from the testing guide. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

IamGalymzhan · 2026-08-14T08:53:20Z

@pkosiec All comments are fixed

Brings feat/testing-kit up to v0.60.0. Three conflicts, all resolved in favour of this branch: - tools/test-helpers.ts — main only reformatted the old implementation; this branch replaced it with a re-export shim over packages/appkit/src/testing. - agents/tests/route-handler-errors.test.ts and dispatch-tool-call.test.ts — this branch migrated both onto createTestPluginContext, a superset of main's raw-stub versions (dispatch-tool-call keeps an extra timeout-abort test). Main migrated Biome -> oxlint+oxfmt, so this commit also reconciles the branch with the new toolchain: the 64 dead biome-ignore comments are dropped from the two conflicted test files, and the shipped testing-kit sources are reformatted under oxfmt's import grouping. Ignore **/.claude in knip, oxlint, and oxfmt. Agent worktrees live under .claude/worktrees/, so every tool was analysing a second full copy of the repo: knip reported hundreds of phantom unused exports and failed the pre-commit hook outright, and a repo-root `oxfmt` would have rewritten another branch's working tree. Co-authored-by: Isaac Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

Both were swept into the oxlint merge from a dirty working tree and corrected later on the branch; folding those corrections in here keeps them out of the follow-up PR. The knip `.claude/**` entry and the `**/.claude` ignorePatterns in oxfmt/oxlint were never needed — nothing in the repo lints or formats that directory. The `packages/appkit` vitest ignoreDependencies entry stays: vitest is a real dependency of the testing entry. apps/dev-playground/client/package-lock.json is restored to origin/main byte-for-byte; npm had run in that directory and pruned its `extraneous: true` entries. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

IamGalymzhan · 2026-08-19T11:30:14Z

Split into a stack. This PR is now scoped to the testing-kit foundation only — the five items in the description above — at 22 files, +2753/−627.

The follow-up work (createTestApp, the never-crash mock WorkspaceClient, app.close(), re-bootable singletons) moved to #540, which is based on this branch. Review this one first; #540 will retarget to main automatically when it merges.

pkosiec

LGTM, great work! Please address one comment before merge.

@pkosiec

`createMockRequest` stored header keys exactly as given while `header()` lowercased the lookup, so a mixed-case override was unreachable: createMockRequest({ obo: { userId: "alice" }, headers: { "X-Forwarded-User": "bob" } }); // header("x-forwarded-user") === "alice" Both keys were kept — ["x-forwarded-access-token", "x-forwarded-user", "X-Forwarded-User"] — and the lowercase one obo seeded still answered, which contradicted the "an explicit override wins" contract documented right above it. Keys are now lowercased on the way in, matching what Node's parser hands Express. Thanks @pkosiec. The existing override test passed because it used a lowercase key, so it is now parametrised over both casings, and the case-insensitivity test additionally pins that every stored key is lowercase. Reverting the fix fails both. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

@pkosiec

Same root cause as the `createMockRequest` fix on the parent branch (#530, found by @pkosiec), and worse here. `Object.assign(headers, reqOptions.headers)` kept case variants as separate keys, and `Headers` **comma-joins** duplicates rather than replacing them: new Headers({ "x-forwarded-user": "alice", "X-Forwarded-User": "bob" }) // -> x-forwarded-user: "alice, bob" So a mixed-case override did not merely lose, it corrupted the value the server received — the "caller headers last" contract broken in a way that produces a plausible-looking string rather than an error. Keys are lowercased before assignment. The existing `/headers` table gained a mixed-case row rather than a new test; reverting the fix fails it. Signed-off-by: Galymzhan <zhangazy2004@gmail.com>

IamGalymzhan added 8 commits August 10, 2026 13:02

IamGalymzhan changed the title ~~Feat/testing kit~~ feat(test-kit) Aug 11, 2026

IamGalymzhan changed the title ~~feat(test-kit)~~ feat(appkit): add testing kit Aug 11, 2026

IamGalymzhan and others added 7 commits August 11, 2026 11:28

Merge branch 'main' into feat/testing-kit

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IamGalymzhan marked this pull request as ready for review August 12, 2026 12:40

IamGalymzhan requested a review from a team as a code owner August 12, 2026 12:40

IamGalymzhan requested a review from atilafassina August 12, 2026 12:40

IamGalymzhan added 2 commits August 12, 2026 15:20

pkosiec reviewed Aug 13, 2026

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Comment thread docs/docs/plugins/testing.md

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IamGalymzhan added 3 commits August 13, 2026 13:22

IamGalymzhan added 3 commits August 13, 2026 14:35

IamGalymzhan added 3 commits August 18, 2026 11:17

Merge remote-tracking branch 'origin/main' into split/foundation

f70f082

IamGalymzhan force-pushed the feat/testing-kit branch from 2eef458 to f70f082 Compare August 19, 2026 11:28

IamGalymzhan mentioned this pull request Aug 19, 2026

feat(appkit): add createTestApp, a never-crash mock client, and app.close() #540

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IamGalymzhan mentioned this pull request Aug 20, 2026

test(playground): smoke-test the playground's own server plugins #542

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IamGalymzhan merged commit 4ea97a4 into main Aug 20, 2026
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📦 Bundle size report

@databricks/appkit

@databricks/appkit-ui

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🤖 AppKit PR bot

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IamGalymzhan commented Aug 14, 2026

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IamGalymzhan commented Aug 11, 2026 •

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`@databricks/appkit`

`@databricks/appkit-ui`

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