Implement+test replaceParams helper method

backend/src/middleware/filterBubble/replaceParams.js

@@ -0,0 +1,23 @@
+export default async function replaceParams(args, context) {
+  const { author = 'all' } = args.filterBubble || {}
+
+  if (author === 'followed') {
+    const session = context.driver.session()
+    let { records } = await session.run(
+      'MATCH(followed:User)<-[:FOLLOWS]-(u {id: $userId}) RETURN followed.id',
+      { userId: context.user.id },
+    )
+    const followedIds = records.map(record => record.get('followed.id'))
+
+    // carefully override `id_in`
+    args.filter = args.filter || {}
+    args.filter.author = args.filter.author || {}
+    args.filter.author.id_in = followedIds
+
+    session.close()
+  }
+
+  delete args.filterBubble
+
+  return args
+}

backend/src/middleware/filterBubble/replaceParams.spec.js

@@ -0,0 +1,99 @@
+import replaceParams from './replaceParams.js'
+
+describe('replaceParams', () => {
+  let args
+  let context
+  let run
+
+  let action = () => {
+    return replaceParams(args, context)
+  }
+
+  beforeEach(() => {
+    args = {}
+    run = jest.fn().mockResolvedValue({
+      records: [{ get: () => 1 }, { get: () => 2 }, { get: () => 3 }],
+    })
+    context = {
+      user: { id: 'u4711' },
+      driver: {
+        session: () => {
+          return {
+            run,
+            close: () => {},
+          }
+        },
+      },
+    }
+  })
+
+  describe('given any additional filter args', () => {
+    describe('merges', () => {
+      it('empty filter object', async () => {
+        args = { filter: {}, filterBubble: { author: 'followed' } }
+        const expected = { filter: { author: { id_in: [1, 2, 3] } } }
+        await expect(action()).resolves.toEqual(expected)
+      })
+
+      it('filter.title', async () => {
+        args = { filter: { title: 'bla' }, filterBubble: { author: 'followed' } }
+        const expected = { filter: { title: 'bla', author: { id_in: [1, 2, 3] } } }
+        await expect(action()).resolves.toEqual(expected)
+      })
+
+      it('filter.author', async () => {
+        args = { filter: { author: { name: 'bla' } }, filterBubble: { author: 'followed' } }
+        const expected = { filter: { author: { name: 'bla', id_in: [1, 2, 3] } } }
+        await expect(action()).resolves.toEqual(expected)
+      })
+    })
+  })
+
+  describe('args == ', () => {
+    describe('{}', () => {
+      it('does not crash', async () => {
+        await expect(action()).resolves.toEqual({})
+      })
+    })
+
+    describe('{ filterBubble: { author: followed } }', () => {
+      beforeEach(() => {
+        args = { filterBubble: { author: 'followed' } }
+      })
+
+      it('returns args object with resolved ids of followed users', async () => {
+        const expected = { filter: { author: { id_in: [1, 2, 3] } } }
+        await expect(action()).resolves.toEqual(expected)
+      })
+
+      it('makes database calls', async () => {
+        await action()
+        expect(run).toHaveBeenCalled()
+      })
+    })
+
+    describe('{ filterBubble: { } }', () => {
+      it('removes filterBubble param', async () => {
+        const expected = {}
+        await expect(action()).resolves.toEqual(expected)
+      })
+
+      it('does not make database calls', async () => {
+        await action()
+        expect(run).not.toHaveBeenCalled()
+      })
+    })
+
+    describe('{ filterBubble: { author: all } }', () => {
+      it('removes filterBubble param', async () => {
+        const expected = {}
+        await expect(action()).resolves.toEqual(expected)
+      })
+
+      it('does not make database calls', async () => {
+        await action()
+        expect(run).not.toHaveBeenCalled()
+      })
+    })
+  })
+})