Moto is a (the?) python AWS mocking package all good python AWS mockers use. The docs are pretty helpful, but personally I like a nice simple example I can copy and paste to start out with, reading is too much effort.
Here's a few I've collected from around the internet. The list is limited to the things I've needed to use so far.
conn = boto3.client("secretsmanager", region_name="us-west-2")
create_secret = conn.create_secret(
result = conn.get_secret_value(SecretId="java-util-test-password")
assert result["SecretString"] == "foosecret"