feat(batch): show the Location of a redirect and save headers

README.md

@@ -269,7 +269,7 @@ EOF
 
 With `--runtime workerd`, one workerd starts and every step runs in it, so a flow over the real bindings (put to KV, then get; D1; an AI binding) runs in one call. The entry is `main` in the wrangler config, so pass no file argument. With `--runtime vite`, one Vite dev server starts and every step goes through it.
 
-One JSON object per line: `method`, `path`, `body`, `headers`, `expect`, `save`. `save` stores a value from the response body by dot path, and later steps use it as `{{id}}` (a whole-variable string keeps the saved type). A string `body` without a `content-type` header goes as a form, or as JSON when it is a JSON object or array. Cookies carry over like in a browser, so a login step signs in the steps after it; a `cookie` header in a step wins. `expect` declares the acceptance criteria: `status` matches exactly, `body` is a deep partial match (declared fields must match, extra response fields are ignored). The output carries the actual `status` and `body`, `pass` per step, and a `summary` — rerun until `failed` is 0. A step without `expect` passes on any 2xx or 3xx and fails on a 4xx or 5xx; to accept a 4xx on purpose, declare it with `expect.status`.
+One JSON object per line: `method`, `path`, `body`, `headers`, `expect`, `save`. `save` stores a value from the response body by dot path, and later steps use it as `{{id}}` (a whole-variable string keeps the saved type). A redirect shows its `location` in the step, and `save` reads a header with `header:`: `"save":{"next":"header:location"}`, then `"path":"{{next}}"` follows the URL a create redirects to. A string `body` without a `content-type` header goes as a form, or as JSON when it is a JSON object or array. Cookies carry over like in a browser, so a login step signs in the steps after it; a `cookie` header in a step wins. `expect` declares the acceptance criteria: `status` matches exactly, `body` is a deep partial match (declared fields must match, extra response fields are ignored). The output carries the actual `status` and `body`, `pass` per step, and a `summary` — rerun until `failed` is 0. A step without `expect` passes on any 2xx or 3xx and fails on a 4xx or 5xx; to accept a 4xx on purpose, declare it with `expect.status`.
 
 ### `snapshot`
 

src/commands/batch/batch.test.ts

@@ -202,6 +202,29 @@ describe('runBatch', () => {
     expect(result.steps[1].body).toEqual({ id: 1, name: 'Momo' })
   })
 
+  it('shows the Location of a redirect and saves a header with header:', async () => {
+    const app = crudApp()
+    app.post('/form', (c) => c.redirect('http://localhost/users/1', 303))
+    const result = await runBatch(
+      app,
+      parseBatch(
+        [
+          '{"method":"POST","path":"/users","body":{"name":"Momo"}}',
+          '{"method":"POST","path":"/form","save":{"next":"header:location"}}',
+          '{"path":"{{next}}","expect":{"status":200,"body":{"name":"Momo"}}}',
+          '{"path":"/users","save":{"x":"header:x-none"}}',
+        ].join('\n')
+      )
+    )
+    expect(result.steps[0].location).toBeUndefined()
+    expect(result.steps[1].location).toBe('http://localhost/users/1')
+    expect(result.steps[1].saved).toEqual({ next: 'http://localhost/users/1' })
+    expect(result.steps[2].path).toBe('/users/1')
+    expect(result.steps[2].pass).toBe(true)
+    expect(result.steps[3].pass).toBe(false)
+    expect(result.steps[3].error).toBe('save: x-none not found in the headers')
+  })
+
   it('passes a step without expect on a 2xx or 3xx', async () => {
     const app = crudApp()
     app.get('/moved', (c) => c.redirect('/users'))

src/commands/batch/batch.ts

@@ -20,6 +20,8 @@ export interface StepResult {
   method: string
   path: string
   status: number
+  /** The Location header of a redirect */
+  location?: string
   body: unknown
   pass: boolean
   expect?: StepExpect
@@ -62,8 +64,9 @@ export const parseBatch = (input: string): BatchStep[] => {
       throw invalid(`Line ${i + 1} is not a JSON object`)
     }
     const step = parsed as Record<string, unknown>
-    if (typeof step.path !== 'string' || !step.path.startsWith('/')) {
-      throw invalid(`Line ${i + 1} needs a "path" starting with /`)
+    // "{{next}}" is a saved path, e.g. from "header:location"
+    if (typeof step.path !== 'string' || !/^(\/|\{\{)/.test(step.path)) {
+      throw invalid(`Line ${i + 1} needs a "path" starting with / or a saved {{name}}`)
     }
     if (step.method !== undefined && typeof step.method !== 'string') {
       throw invalid(`Line ${i + 1}: "method" must be a string`)
@@ -252,7 +255,8 @@ export const runBatch = async (
   const results: StepResult[] = []
 
   for (const step of steps) {
-    const path = interpolate(step.path, vars)
+    // A saved absolute URL (a Location) goes to the same app
+    const path = String(interpolate(step.path, vars)).replace(/^https?:\/\/[^/]+/, '')
     const headers: Record<string, string> = {
       ...sharedHeaders,
       ...interpolate(step.headers ?? {}, vars),
@@ -292,10 +296,12 @@ export const runBatch = async (
       }
     }
 
+    const location = response.headers.get('location')
     const result: StepResult = {
       method: step.method,
       path,
       status: response.status,
+      ...(location === null ? {} : { location }),
       body,
       pass: true,
       ...(step.expect === undefined ? {} : { expect: interpolate(step.expect, vars) }),
@@ -327,10 +333,15 @@ export const runBatch = async (
     if (step.save) {
       const saved: Record<string, unknown> = {}
       for (const [name, savePath] of Object.entries(step.save)) {
-        const value = getByPath(body, savePath)
+        // "header:location" reads a header, e.g. the URL a create redirects to
+        const header = savePath.startsWith('header:') ? savePath.slice(7) : undefined
+        const value =
+          header === undefined
+            ? getByPath(body, savePath)
+            : (response.headers.get(header) ?? undefined)
         if (value === undefined) {
           result.pass = false
-          result.error = `save: ${savePath} not found in the body`
+          result.error = `save: ${header ?? savePath} not found in the ${header ? 'headers' : 'body'}`
         } else {
           vars[name] = value
           saved[name] = value

src/commands/batch/index.ts

@@ -26,6 +26,7 @@ EOF`,
   notes: [
     'Runs many requests in one call, in order, against one app instance — in-memory state carries between steps. One JSON object per line: {"method","path","body","headers","expect","save"}.',
     '"save" stores a value from the response body by dot path (e.g. {"id":".id"}), and later steps use it as {{id}}. A whole-variable string like "{{id}}" keeps the saved type.',
+    'A redirect shows its "location". "save" reads a header with "header:", e.g. {"next":"header:location"}, then {"path":"{{next}}"} follows it.',
     'Cookies carry over like in a browser: a login step that sets a cookie signs in the steps after it. A "cookie" header in a step wins.',
     'Declare the acceptance criteria in "expect": {"status":201} and/or {"body":{...}} (a deep partial match — declared fields must match, extra response fields are ignored). Turn the spec into batch lines and rerun until "failed" is 0 — comparing a spec table by eye misses lines.',
     'A step without "expect" passes on any 2xx or 3xx and fails on a 4xx or 5xx. To accept a 4xx on purpose, declare it: {"expect":{"status":404}}.',