Postman parameterized tests with actual values and expected errors for same request

Question

I have request with number of tests cases, same endpoint, different actual values, different expected error messages. I would like to create parameterized request sending particular value and check particular error message from list with all of the cases. Request body:

{
"username": "{{username}}",
"password": "{{password}}",
 ...

}

Response:

{
"error_message": "{{error_message}}",
"error_code": "{{error_code}}"
}

Error message changes due to different cases:

1. Missed username
2. Missed password
3. Incorrect password or username
4. etc

Now, I have separate request on each case. Question:

Is there way have 1 request with set of different values, checking particular error messages/codes?

Answer 1

Create a csv:

username,password,error_message,error_code
username1,password1,errormessage1,errorcode1
username1,password1,errormessage1,errorcode1

Now use this as data file in collection runner or newman.

variable name is same as the column name and, for each iteration you will have corresponding row-column value as the variable value. Eg for iteration1 username will be username1

. As danny mentioned postman has a really rich documentation that you can make use of

https://learning.postman.com/docs/running-collections/working-with-data-files/

Answer 2

Adding another answer on how to run data driven from same request:

Create a environment variable called "csv" and copy the below content and paste it as value:

username,password,error_message,error_code
username1,password1,errormessage1,errorcode1
username1,password1,errormessage1,errorcode1

Now in pr-request add :

if (!pm.variables.get("index")) {

    const parse = require('csv-parse/lib/sync')
    //Environmental variable where we copy-pasted the csv content
    const input = pm.environment.get("csv");
    const records = parse(input, {
        columns: true,
        skip_empty_lines: true
    })

    pm.variables.set("index", 0)
    pm.variables.set("records", records)
}

records = pm.variables.get("records")
index = pm.variables.get("index")
if (index !== records.length) {
    for (let i of Object.entries(records[index])) {
        pm.variables.set(i[0], i[1])
    }
    pm.variables.set("index", ++index)
    pm.variables.get("index")===records.length?null:postman.setNextRequest(pm.info.requestName)
}

Now you can run data driven for that one particular request:

Eg collection:

https://www.getpostman.com/collections/eb144d613b7becb22482

use the same data as environment variable content , now run the collection using collection runner or newman

Output