Find replace entire string line of variable text using batch script

Question

Working on a batch script that will modify package.json file.

Basically, I need to replace the "test" portion of every json file.

This is a sample snippet:

  "scripts": {
    "test": "any text can go here"
  },

What I want to do is replace the entire "test" line with:

"test": "jest --coverage"

I have only come up with a script that replaces a string (without spaces):

SETLOCAL ENABLEDELAYEDEXPANSION

for /f "delims=" %%a in (temp.txt) do (
    SET s=%%a
    SET s=!s:test=newText!
    echo !s!>>yourtempfilename.txt
)
pause

Can anyone help me modify this so that: - it can accommodate a string with spaces - it can replace the entire line with "test" considering "any text can go here" value is always different

Please note though that I cannot use any other programs/commands such as sed or fnr.bat or something.

Answer 1

As Compo already commented, batch isn't the right tool for the job, but when you can't use anything other (like PowerShell):

@echo off
setlocal disabledelayedexpansion
set "newtext=some other text here"
(for /f "tokens=1* delims=]" %%a in ('find /n /v "" temp.txt') do (
  echo %%b|findstr /rc:"\ *\"test\":\ \".*\"" >nul && (
    for /f "delims=:" %%c in ("%%b") do echo %%c: "%newtext%"
    ) || echo/%%b
))>yourtempfilename.txt 2>nul

It keeps formatting and empty lines but has some problems with certain poison characters (that's why 2>nul ; the output is ok though)