diff --git a/js/tests/personal-shopper_test.mjs b/js/tests/personal-shopper_test.mjs
new file mode 100644
index 00000000..a6da757c
--- /dev/null
+++ b/js/tests/personal-shopper_test.mjs
@@ -0,0 +1,375 @@
+import * as cp from 'child_process'
+import fs from 'fs/promises'
+import { join, resolve, isAbsolute } from 'path'
+import { tmpdir } from 'os'
+import { promisify } from 'util'
+const mkdir = fs.mkdir
+const rmdir = fs.rmdir
+const readFile = fs.readFile
+
+const exec = promisify(cp.exec)
+
+export const tests = []
+const name = 'personal-shopper'
+const getRandomElem = () =>
+  Math.random()
+    .toString(36)
+    .substring(7)
+export const setup = async () => {
+  const dir = tmpdir()
+  const elems = {}
+  const randomElem = getRandomElem()
+  const anotherElem = getRandomElem()
+  const commands = ['add', 'rm', 'delete', 'create', 'ls', 'help']
+  // check if already exists and rm
+  const exists = await fs
+    .stat(`${dir}/${name}`)
+    .catch((err) => (err.code === 'ENOENT' ? 'file not found: good.' : err))
+  if (Object.keys(exists).length) {
+    await rmdir(`${dir}/${name}`, { recursive: true })
+  }
+
+  await mkdir(`${dir}/${name}`)
+
+  return { tmpPath: `${dir}/${name}`, elems, commands, randomElem, anotherElem }
+}
+const assistInShopping = async ({
+  file,
+  keyword,
+  elem,
+  number,
+  ctx,
+  path,
+  eq,
+}) => {
+  // check if file exists before testing create - if exists, rm it
+  if (keyword === 'create') {
+    const out = await fs
+      .stat(`${ctx.tmpPath}/${file}`)
+      .catch((err) =>
+        err.code === 'ENOENT' ? 'output file not found: normal' : err,
+      )
+    if (out.birthtime) await fs.rm(`${ctx.tmpPath}/${file}`)
+  }
+
+  const scriptPath = join(resolve(), path)
+  const { stdout, stderr } = await exec(
+    `node ${scriptPath} ${file} ${keyword} ${elem || ''} ${number || ''}`,
+    {
+      cwd: ctx.tmpPath,
+    },
+  )
+  const out = await readFile(`${ctx.tmpPath}/${file}`, 'utf8').catch((err) =>
+    err.code === 'ENOENT' ? 'output file not found' : err,
+  )
+
+  if (keyword === 'create') return eq(out, '{}')
+
+  if (keyword === 'add' || keyword === 'rm') {
+    if (!elem) return eq(stderr.trim(), 'No elem specified.')
+    if (number && isNaN(Number(number)) && keyword === 'rm') {
+      return eq(stderr.trim(), 'Unexpected request: nothing has been removed.')
+    }
+    const content = JSON.parse(out)
+
+    const addValue = !number || isNaN(Number(number)) ? 1 : number
+    const rmValue = !number ? ctx.elems[elem] : number
+    const newNumber =
+      keyword === 'add'
+        ? (ctx.elems[elem] || 0) + addValue
+        : (ctx.elems[elem] || 0) - rmValue
+    const state = newNumber > 0 ? content[elem] === newNumber : !content[elem]
+    ctx.elems[elem] = newNumber > 0 ? newNumber : 0
+    return state
+  }
+
+  if (keyword === 'ls') {
+    const content = JSON.parse(out)
+    const entries = Object.entries(content)
+    return entries.length
+      ? eq(entries.map(([k, v]) => `- ${k} (${v})`).join('\n'), stdout.trim())
+      : eq(stdout.trim(), 'Empty list.')
+  }
+
+  if (keyword === 'help' || !keyword) {
+    return ctx.commands.every((c) => stdout.includes(c))
+  }
+
+  if (keyword === 'delete') return eq(out, 'output file not found')
+}
+
+tests.push(async ({ path, eq, ctx }) => {
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'create',
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // no elem specifiel, should log an error
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'add',
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // add NaN value, should add 1
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'add',
+    elem: ctx.randomElem,
+    number: 'someNaN',
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // add without number, should add 1
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'add',
+    elem: ctx.randomElem,
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // add random value, between 5 and 15
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'add',
+    elem: ctx.randomElem,
+    number: Math.floor(Math.random() * (15 - 5) + 5),
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // add negative value, bigger than current value - should delete the entry
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'add',
+    elem: ctx.randomElem,
+    number: -Math.floor(Math.random() * (25 - 16) + 16),
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // add value to prepare next test
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'add',
+    elem: ctx.randomElem,
+    number: Math.floor(Math.random() * (25 - 16) + 16),
+  })
+})
+tests.push(async ({ path, eq, ctx }) => {
+  // add negative exact nm of elem -> 0, should delete the entry
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'add',
+    elem: ctx.randomElem,
+    number: -ctx.elems[ctx.randomElem],
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // no elem specified, should log an error
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'rm',
+    // no elem, no number
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // rm elem which is not in the list, should do nothing
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'rm',
+    elem: ctx.randomElem,
+    // no number
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // rm negative value, should add it
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'rm',
+    elem: ctx.randomElem,
+    number: -Math.floor(Math.random() * (25 - 16) + 16),
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // rm positive value, smaller than current value -> should substract it from current value
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'rm',
+    elem: ctx.randomElem,
+    number: Math.floor(Math.random() * (10 - 5) + 5),
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // should print the list with the elem as expected inside
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'ls',
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // rm without number, should delete the entry
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'rm',
+    elem: ctx.randomElem,
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // should print an empty list
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'ls',
+  })
+})
+
+// add 2 elems - tests: ls several values, rm more or same value as current
+tests.push(async ({ path, eq, ctx }) => {
+  // add value to prepare next test
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'add',
+    elem: ctx.randomElem,
+    number: Math.floor(Math.random() * (25 - 16) + 16),
+  })
+})
+tests.push(async ({ path, eq, ctx }) => {
+  // add value to prepare next test
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'add',
+    elem: ctx.anotherElem,
+    number: ctx.elems[ctx.randomElem], // add same value than randomelem
+  })
+})
+tests.push(async ({ path, eq, ctx }) => {
+  // test ls with several elems
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'ls',
+  })
+})
+tests.push(async ({ path, eq, ctx }) => {
+  // test where rm exat nm of elem -> 0, delete the entry
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'rm',
+    elem: ctx.randomElem,
+    number: ctx.elems[ctx.randomElem],
+  })
+})
+tests.push(async ({ path, eq, ctx }) => {
+  // test where rm more than nm of elem -> <0, delete the entry
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'rm',
+    elem: ctx.randomElem,
+    number: 2000,
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // should print the helper
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'help',
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  // should print the helper
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: '',
+  })
+})
+
+tests.push(async ({ path, eq, ctx }) => {
+  return assistInShopping({
+    path,
+    eq,
+    ctx,
+    file: `${name}.json`,
+    keyword: 'delete',
+  })
+})
+
+Object.freeze(tests)
diff --git a/subjects/personal-shopper/README.md b/subjects/personal-shopper/README.md
new file mode 100644
index 00000000..898ab65b
--- /dev/null
+++ b/subjects/personal-shopper/README.md
@@ -0,0 +1,111 @@
+## personal-shopper
+
+### Instructions
+
+You know your guests, but don't forget you have to feed them if you want to be considered as a good host.
+
+Create a `personal-shopper.mjs` script that:
+- Takes a file as first argument, for example `shopping-list.json`
+- Takes one of these keywords as second argument:
+  - `create`: create the file
+  - `delete`: delete the file
+  - `add`: add a new element to the list in the file.
+    - This command line must take a third argument which is the name of the new entry in your list. If no third argument is passed, console must print this error: `No elem specified.`.
+    - This command line could take a fourth argument which is the number of elements you want for this new entry.
+      - If there is no 4rth argument or the 4rth argument is `NaN`, 1 would be the value by default.
+      - If the entry already exists, it would add 1 or more to the original value.
+      - Using a negative number must behave as `rm` command.
+  - `rm`: remove an element from the list in the file
+    - This command line must take a third argument which is the name of the entry to remove from the list.
+      - If no third argument is passed, console must print this error: `No elem specified.`.
+      - If the entry does not exists, it does nothing.
+    - This command line could take a fourth argument which is the number of elements you want to delete from this entry.
+      - If there is no 4rth argument: it remove the entry.
+      - If the 4rth argument is `NaN`, nothing is removed and console must print this error `Unexpected request: nothing has been removed`.
+      - If the 4rth argument is a number, it will substract this number from the original value (if the new value is <= 0, it will remove the entry).
+      - Using a negative number must behave as `add` command.
+  - `help`: print all the command lines available, with a description of it (specifications in the examples)
+  - `ls` or no more arguments: print the list in the console.
+    - Each line is formated like this: `- element (number)`
+    - If the list is empty, this message should appear in console: `Empty list.`.
+
+#### Examples
+
+- `node personal-shopper.mjs shopping-list.json create` would create the file
+- `node personal-shopper.mjs shopping-list.json delete` would remove the file
+
+- `node personal-shopper.mjs shopping-list.json add "tzatziki pot"` would update the content of the file like:
+```json
+'{
+  "tzatziki pot": 1
+}'
+```
+
+- `node personal-shopper.mjs shopping-list.json add carrots 5` would update the content of the file like:
+```json
+'{
+  "tzatziki pot": 1,
+  "carrots": 5
+}'
+```
+
+- `node personal-shopper.mjs shopping-list.json add carrots 2` would update the content of the file like:
+```json
+'{
+  "tzatziki pot": 1,
+  "carrots": 7
+}'
+```
+
+- `node personal-shopper.mjs shopping-list.json rm carrots 4` would update the content of the file like:
+```json
+'{
+  "tzatziki pot": 1,
+  "carrots": 3
+}'
+```
+
+- `node personal-shopper.mjs shopping-list.json rm carrots` would update the content of the file like:
+```json
+'{
+  "tzatziki pot": 1
+}'
+```
+
+- `node personal-shopper.mjs shopping-list.json rm carrots -3` would update the content of the file like:
+```json
+'{
+  "tzatziki pot": 1,
+  "carrots": 3
+}'
+```
+
+- `node personal-shopper.mjs shopping-list.json add carrots -3` would update the content of the file like:
+```json
+'{
+  "tzatziki pot": 1
+}'
+```
+
+- `node personal-shopper.mjs shopping-list.json ls` would print the list in your console like this:
+```
+- tzatziki pot (1)
+```
+
+- `node personal-shopper.mjs help` would print a list of all available commands in your console :
+```
+Commands:
+- create: takes a filename as argument and create it (should have `.json` extension specified)
+- delete: takes a filename as argument and delete it
+<!-- etc. -->
+```
+
+### Notions
+
+- [Node file system: `rm`](https://nodejs.org/docs/latest/api/fs.html#fs_fspromises_rm_path_options)
+- [Node file system: `writeFile`](https://nodejs.org/docs/latest/api/fs.html#fs_fspromises_writefile_file_data_options)
+- [`JSON.parse()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse)
+- [`JSON.stringify()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify)
+- [`isNaN()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/isNaN)
+- [`Number()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)
+- [`console.error()`](https://developer.mozilla.org/en-US/docs/Web/API/Console/error)