Adding key name to value using jq

I am trying to dynamically assign the key name as its value in my json

This is the json i am using:

{
    "test1": "",
    "test2": "",
    "test3": ""
}

the result i would like to obtain looks like this:

{
    "test1": "test1",
    "test2": "test2",
    "test3": "test3"
}

I am not familiar with jq and the closest result i got is using:

keys[] as $key | {"\($key)": "\($key)"} | .

here is the output:

{
  "test1": "test1"
}
{
  "test2": "test2"
}
{
  "test3": "test3"
}

>Solution :

with_entries lets you manipulate .key and .value for each field. Just set one to the value of the other:

with_entries(.value = .key)

{
  "test1": "test1",
  "test2": "test2",
  "test3": "test3"
}

Demo

Following your approach, you might want to consider reduce for an iterative manipulation, and keys_unsorted which acts like keys but produces the keys in the original (unsorted) order:

reduce keys_unsorted[] as $key (.; .[$key] = $key)

Demo