feat: anyware hook retries (#904)

src/layers/5_client/client.extend.test.ts

@@ -1,10 +1,9 @@
 /* eslint-disable */
-import { ExecutionResult } from 'graphql'
 import { describe, expect } from 'vitest'
 import { db } from '../../../tests/_/db.js'
 import { createResponse, test } from '../../../tests/_/helpers.js'
 import { Graffle } from '../../../tests/_/schema/generated/__.js'
-import { GraphQLExecutionResult } from '../../legacy/lib/graphql.js'
+import { oops } from '../../lib/anyware/specHelpers.js'
 
 const client = Graffle.create({ schema: 'https://foo', returnMode: 'dataAndErrors' })
 const headers = { 'x-foo': 'bar' }
@@ -38,3 +37,26 @@ describe(`entrypoint request`, () => {
     expect(await client2.query.id()).toEqual(db.id)
   })
 })
+
+test('can retry failed request', async ({ fetch }) => {
+  fetch
+    .mockImplementationOnce(async () => {
+      throw oops
+    })
+    .mockImplementationOnce(async () => {
+      throw oops
+    })
+    .mockImplementationOnce(async () => {
+      return createResponse({ data: { id: db.id } })
+    })
+  const client2 = client.retry(async ({ exchange }) => {
+    let result = await exchange()
+    while (result instanceof Error) {
+      result = await exchange()
+    }
+    return result
+  })
+  const result = await client2.query.id()
+  expect(result).toEqual(db.id)
+  expect(fetch.mock.calls.length).toEqual(3)
+})

src/layers/5_client/client.ts

@@ -39,6 +39,7 @@ export type SelectionSetOrIndicator = 0 | 1 | boolean | object
 export type SelectionSetOrArgs = object
 
 export interface Context {
+  retry: undefined | Anyware.Extension2<Core.Core, { retrying: true }>
   extensions: Anyware.Extension2<Core.Core>[]
   config: Config
 }
@@ -65,6 +66,7 @@ export type Client<$Index extends Schema.Index | null, $Config extends Config> =
     )
   & {
       extend: (extension: Anyware.Extension2<Core.Core>) => Client<$Index, $Config>
+      retry: (extension: Anyware.Extension2<Core.Core, { retrying: true }>) => Client<$Index, $Config>
     }
 
 export type ClientTyped<$Index extends Schema.Index, $Config extends Config> =
@@ -147,9 +149,10 @@ type Create = <
 
 export const create: Create = (
   input_,
-) => createInternal(input_, { extensions: [] })
+) => createInternal(input_, { extensions: [], retry: undefined })
 
 interface CreateState {
+  retry?: Anyware.Extension2<Core.Core, { retrying: true }>
   extensions: Anyware.Extension2<Core.Core>[]
 }
 
@@ -251,6 +254,7 @@ export const createInternal = (
   }
 
   const context: Context = {
+    retry: state.retry,
     extensions: state.extensions,
     config: {
       returnMode,
@@ -260,6 +264,7 @@ export const createInternal = (
   const run = async (context: Context, initialInput: HookInputEncode) => {
     const result = await Core.anyware.run({
       initialInput,
+      retryingExtension: context.retry,
       extensions: context.extensions,
     }) as GraffleExecutionResult
     return handleReturn(context, result)
@@ -296,6 +301,9 @@ export const createInternal = (
       // todo test that adding extensions returns a copy of client
       return createInternal(input, { extensions: [...state.extensions, extension] })
     },
+    retry: (extension: Anyware.Extension2<Core.Core, { retrying: true }>) => {
+      return createInternal(input, { ...state, retry: extension })
+    },
   }
 
   // todo extract this into constructor "create typed client"

src/lib/anyware/__.test-d.ts

@@ -1,5 +1,6 @@
 /* eslint-disable */
 
+import { run } from 'node:test'
 import { expectTypeOf, test } from 'vitest'
 import { Result } from '../../../tests/_/schema/generated/SchemaRuntime.js'
 import { ContextualError } from '../errors/ContextualError.js'
@@ -32,6 +33,16 @@ test('run', () => {
     (input: {
       initialInput: InputA
       options?: Anyware.Options
+      retryingExtension?: (input: {
+        a: SomeHook<
+          (input?: InputA) => MaybePromise<
+            Error | {
+              b: SomeHook<(input?: InputB) => MaybePromise<Error | Result>>
+            }
+          >
+        >
+        b: SomeHook<(input?: InputB) => MaybePromise<Error | Result>>
+      }) => Promise<Result>
       extensions: ((input: {
         a: SomeHook<
           (input?: InputA) => MaybePromise<{

src/lib/anyware/getEntrypoint.ts

@@ -1,7 +1,7 @@
 // import type { Extension, HookName } from '../../layers/5_client/extension/types.js'
 import { analyzeFunction } from '../analyzeFunction.js'
 import { ContextualError } from '../errors/ContextualError.js'
-import type { ExtensionInput, HookName } from './main.js'
+import type { HookName, NonRetryingExtensionInput } from './main.js'
 
 export class ErrorAnywareExtensionEntrypoint extends ContextualError<
   'ErrorGraffleExtensionEntryHook',
@@ -25,7 +25,7 @@ export type ExtensionEntryHookIssue = typeof ExtensionEntryHookIssue[keyof typeo
 
 export const getEntrypoint = (
   hookNames: readonly string[],
-  extension: ExtensionInput,
+  extension: NonRetryingExtensionInput,
 ): ErrorAnywareExtensionEntrypoint | HookName => {
   const x = analyzeFunction(extension)
   if (x.parameters.length > 1) {

src/lib/anyware/lib.ts

@@ -0,0 +1 @@
+export const defaultFunctionName = `anonymous`

src/lib/anyware/main.test.ts

@@ -1,8 +1,10 @@
 /* eslint-disable */
 
 import { describe, expect, test, vi } from 'vitest'
+import { Errors } from '../errors/__.js'
 import type { ContextualError } from '../errors/ContextualError.js'
-import { core, initialInput, oops, run, runWithOptions } from './specHelpers.js'
+import { createRetryingExtension } from './main.js'
+import { core, oops, run, runWithOptions } from './specHelpers.js'
 
 describe(`no extensions`, () => {
   test(`passthrough to implementation`, async () => {
@@ -203,7 +205,7 @@ describe(`errors`, () => {
     `)
   })
 
-  test(`implementation throws`, async () => {
+  test(`if implementation fails, without extensions, result is the error`, async () => {
     core.hooks.a.mockReset().mockRejectedValueOnce(oops)
     const result = await run() as ContextualError
     expect({
@@ -221,4 +223,88 @@ describe(`errors`, () => {
       }
     `)
   })
+  test('calling a hook twice leads to clear error', async () => {
+    let neverRan = true
+    const result = await run(async ({ a }) => {
+      await a()
+      await a()
+      neverRan = false
+    }) as ContextualError
+    expect(neverRan).toBe(true)
+    const cause = result.cause as ContextualError
+    expect(cause.message).toMatchInlineSnapshot(
+      `"Only a retrying extension can retry hooks."`,
+    )
+    expect(cause.context).toMatchInlineSnapshot(`
+      {
+        "extensionsAfter": [],
+        "hookName": "a",
+      }
+    `)
+  })
+})
+
+describe('retrying extension', () => {
+  test('if hook fails, extension can retry, then short-circuit', async () => {
+    core.hooks.a.mockReset().mockRejectedValueOnce(oops).mockResolvedValueOnce(1)
+    const result = await run(createRetryingExtension(async function foo({ a }) {
+      const result1 = await a()
+      expect(result1).toEqual(oops)
+      const result2 = await a()
+      expect(typeof result2.b).toEqual('function')
+      expect(result2.b.input).toEqual(1)
+      return result2.b.input
+    }))
+    expect(result).toEqual(1)
+  })
+
+  describe('errors', () => {
+    test('not last extension', async () => {
+      const result = await run(
+        createRetryingExtension(async function foo({ a }) {
+          return a()
+        }),
+        async function bar({ a }) {
+          return a()
+        },
+      )
+      expect(result).toMatchInlineSnapshot(`[ContextualError: Only the last extension can retry hooks.]`)
+      expect((result as Errors.ContextualError).context).toMatchInlineSnapshot(`
+        {
+          "extensionsAfter": [
+            {
+              "name": "bar",
+            },
+          ],
+        }
+      `)
+    })
+    test('call hook twice even though it succeeded the first time', async () => {
+      let neverRan = true
+      const result = await run(
+        createRetryingExtension(async function foo({ a }) {
+          const result1 = await a()
+          expect('b' in result1).toBe(true)
+          await a() // <-- Extension bug here under test.
+          neverRan = false
+        }),
+      )
+      expect(neverRan).toBe(true)
+      expect(result).toMatchInlineSnapshot(
+        `[ContextualError: There was an error in the extension "foo".]`,
+      )
+      expect((result as Errors.ContextualError).context).toMatchInlineSnapshot(
+        `
+        {
+          "extensionName": "foo",
+          "hookName": "a",
+          "source": "extension",
+        }
+      `,
+      )
+      expect((result as Errors.ContextualError).cause).toMatchInlineSnapshot(
+        `[ContextualError: Only after failure can a hook be called again by a retrying extension.]`,
+      )
+    })
+  })
 })