documentation: Update requirements to run the tests

Because Postgres database is required for tests to pass
we explicitly says about it in the documentation and provide
a simple instruction on how to get one.
The change also updates documentation of the glsql package
to align it with the new approach. The old info that is not
actual anymore is removed.

1 files changed, 10 insertions, 0 deletions

diff --git a/doc/beginners_guide.md b/doc/beginners_guide.md
index 2a482f3cb..d5ef0ef0a 100644
--- a/doc/beginners_guide.md
+++ b/doc/beginners_guide.md
@@ -181,6 +181,16 @@ Generally, you should always write new tests in Go even when testing Ruby code,
 since we're planning to gradually rewrite everything in Go and want to avoid
 having to rewrite the tests as well.
 
+Because praefect lives in the same repository we need to provide database connection
+information in order to run tests for it successfully. To get more info check out
+[glsql](../internal/praefect/datastore/glsql/doc.go) package documentation.
+The easiest way to set up a Postgres database instance is to run it as a Docker container.
+You can do it using command:
+```bash
+docker rm -f $(docker ps -q --all -f name=praefect-pg) > /dev/null 2>1; \
+docker run --name praefect-pg -p 5432:5432 -e POSTGRES_HOST_AUTH_METHOD=trust -d postgres:12.6
+```
+
 To run the full test suite, use `make test`.
 You'll need some [test repositories](test_repos.md), you can set these up with `make prepare-tests`.