b6194f08

By: Tom Sydney Kerckhove <syd@cs-syd.eu>

sqitch-postgres: deploy migrations into a random non-public schema

The harness deployed (and snapshotted) migrations in the public schema, so a
migration that hardcodes a schema in an information_schema lookup -- a deploy
guard or verify with table_schema = 'public' -- passed unnoticed even though
it silently misbehaves (a skipped ALTER, a verify that finds nothing) when
deployed into a non-default schema.

Deploy into a fresh, randomly-named non-public schema instead, created and
dropped (CASCADE) via a SetupFunc so tests leave nothing behind. sqitch
connections are scoped to it via PGOPTIONS search_path; pooled actions via
useTestSchema; and the schema snapshots now follow current_schema(). A
migration that hardcodes a schema now fails the existing deploy --verify
checks (a new toy-sqitch-hardcoded-public negative fixture exercises this).

New API: randomSchemaSetupFunc (generates the name and supplies it),
schemaSetupFunc (takes a name; for sharing one schema across two databases),
randomSchemaName, useTestSchema. Breaking: sqitchTargetFromOptions now takes
the schema as its first argument. Both packages -> 0.1.0.0.

Timeline