Browser mode: vi.mock of a non-JS module (svg, json, ?query assets) is ignored with import map mocks (5.1.0) #11952

Describe the bug

Since 5.1.0 serves browser mocks through an import map (#11534), vi.mock of any module that Vite imports with an explicit ?import query is silently ignored: the real module loads and no error is reported. That is every import that is not a JS or CSS request: .svg, .png, .json, ./icon.svg?component, etc.

resolveMockImportMap (packages/browser/src/node/mocks.ts) builds the key from module.url (/icon.svg?component, /plain.svg, /data.json), adding only v= and t=. Vite's import analysis emits /icon.svg?import&component, /plain.svg?import, /data.json?import (isExplicitImportRequired → injectQuery(url, 'import'), which puts import first), so the key never matches. With browser.importMapMocks: false the same test passes.

Suggested fix: apply Vite's rule when building the key. If the URL is not a JS/CSS request, inject import the way injectQuery does (/a.svg?component → /a.svg?import&component). Writing the mock specifier as ./icon.svg?import&component makes the SVG cases pass, which confirms the key mismatch. JSON then resolves to undefined, so the manual-mock shim for JSON may need a look too.

Reproduction

https://github.com/mohammad-naji7/vitest-import-map-mock-repro

npm install && npx playwright install chromium, then:

• npm test: 1 passed, 3 failed (the svg, svg?component and json mocks are ignored)
• npm run test:no-import-map: 4 passed, with browser.importMapMocks: false

System Info

macOS 27.2, Apple M3 Pro
Node 26.10.0, npm 11.19.1
vitest 5.1.0, @vitest/browser 5.1.0, @vitest/browser-playwright 5.1.0, vite 8.3.8, playwright 1.61.1 (Chromium, headless)

Used Package Manager

npm

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