How to rename a function in firemin

renameFunction.js

import { assocNodePath, findNodeInTree, findNodePathInTree } from 'firetree'
import { createIdentifier } from 'firetree/parser/pipes'
import { Identifier } from 'firetree/parser/tokens'
import { List } from 'immutable'
import { propEq } from 'ramda'

import { measure } from '../../utils'

const renameFunction = measure(
  (context, ast, functionId) => `renameFunction:${functionId}`,
  (context, ast, functionId, newName) => {
    const functionDeclaration = findNodeInTree(propEq('id', functionId), ast)

    const { identifier } = functionDeclaration
    const identifierPath = findNodePathInTree(propEq('id', identifier.id), ast)

    // NOTE: The assocNotePath method automatically reidentifies all nodes in the tree 
    // within that path that was modified. This will automatically regenerate all of the
    // FunctionDeclaration metadata. So only the target identifer that represents the
    // function's name needs to be changed and assocNodePath will do the rest.
    return assocNodePath(
      context,
      identifierPath,
      createIdentifier({
        id: identifier.id,
        tokenList: List([Identifier.parse(context, newName)])
      }),
      ast
    )
  }
)

export default renameFunction

renameFunction.test.js

import { generateString, setupContext, tokenize } from 'firetree'
import { FunctionDeclaration } from 'firetree/parser/nodes'

import renameFunction from './renameFunction'

describe('renameFunction', () => {
  test('should rename empty function with name', async () => {
    const context = setupContext({
      logger: console
    })
    const declaration = FunctionDeclaration.parse(
      context,
      await tokenize(context, { string: 'function test() { return true }' })
    )

    const result = renameFunction(context, declaration, declaration.id, 'f1')

    expect(generateString(context, { ast: result })).toBe('function f1() { return true }')
  })

  test('should rename function but NOT rename parameter with same name', async () => {
    const context = setupContext({
      logger: console
    })
    const declaration = FunctionDeclaration.parse(
      context,
      await tokenize(context, { string: 'function test(test) { return test }' })
    )

    const result = renameFunction(context, declaration, declaration.id, 'f1')

    expect(generateString(context, { ast: result })).toBe('function f1(test) { return test }')
  })
})