travis-ci postgres `SELECT EXISTS` query return different result - postgresql

Question

I am working on some tests with pg-promise involve dropping a table and recreate a table.
All tests passes on my local machine. But ontravis-ci, it seems to skipp all the DROP TABLE ... SQL, resulting tests fail.
Anyone has any idea why? Is it a permission issue?
Is there a way for me to further debug this, like connect to travis-ci postgres sever?
Update: I didnt put any code cuz all tests pass on my local env, so I thought it is just a travis-ci issue. The below are the bit that I think traivs-ci is skipping.
afterEach('cleanup tables', (done) => {
db.none('DROP TABLE $1~', 'syncTest')
.then(done)
.catch(() => done());
});
beforeEach('cleanup tables', (done) => {
db.none('DROP TABLE $1~', 'syncTest')
.then(done)
.catch(() => done());
});
Update2: After some further tests, it turns out that the test fail was because that
db.one('SELECT EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name=$1)', [tableName])
was not returning expected value. The query is returning { '?column?': false } on travis, but returning { exists: false } on my local env.
Is this a travis-ci issue? or postgres version issue?

Answer 1

Most likely it is because your test sequence is wrong, which is subject to a race condition, which you only see on Travis Ci because it is much busier than your local machine when running the tests.
To start with, try replacing your DROP TABLE name with DROP TABLE IF EXISTS name.
And then you may try using CREATE TABLE IF NOT EXISTS name...