Prisma findFirstOrThrow does not throw - prisma

Question

Using prisma I am trying to write some tests, however the findFirstOrThrow method (https://www.prisma.io/docs/reference/api-reference/prisma-client-reference#findfirstorthrow) does not seem to throw when nothing should be found. Instead it is returning the first database record it finds.
The following piece of code is what I am testing
console.log('sessionId', this.ctx.session?.user?.id);
const author = await this.db.author.findFirstOrThrow({
where: { userId: this.ctx.session?.user?.id },
select: { id: true },
});
console.log({ author });
And in my test output I get the following logs
RERUN src/api/service.ts x31
stdout | src/api/service.test.ts > BlockService > block creation > without an author
sessionId undefined
stdout | src/api/service.test.ts > BlockService > block creation > without an author
{ author: { id: 'cle79pisg007hb2b8rhpii1ws' } }
So even though the this.ctx.session?.user?.id is undefined, prisma still returns the first author in the table.
What I've tried so far:
When not populating the authors table in the test it will throw.
When populating the authors table with a single author it will return this author
When giving an explicit undefined as the userId it will still returns the first record
edit: I use prisma ^4.8.0

Answer 1

This is the expected behaviour.
If you will pass undefined then it is equivalent to not passing any userId.
So, the query is equivalent to the following:
const author = await this.db.author.findFirstOrThrow({
where: { },
select: { id: true },
});
And this query would return the first record from database.
For reference, here is the section that defines this behaviour.