From a25a6e92793537277b796ca9751f77ac4b082d64 Mon Sep 17 00:00:00 2001
From: Bryan Newbold <bnewbold@robocracy.org>
Date: Tue, 8 Jan 2019 17:26:03 -0800
Subject: integrate pg_tmp into tests

---
 rust/README.md       |  4 ++++
 rust/src/lib.rs      | 26 +++++++++++++++++++++-----
 rust/tests/pg_tmp.sh |  1 +
 3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/rust/README.md b/rust/README.md
index decfc74d..33249a44 100644
--- a/rust/README.md
+++ b/rust/README.md
@@ -42,6 +42,10 @@ Build and run:
 
 Tests:
 
+    cargo test
+
+    # if you get weird postgres errors, try running only one test at a time
+    # (slow and conservative)
     cargo test -- --test-threads 1
 
 Note that most "integration" level tests are written in python and run by
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index b3e6c813..0d9ef813 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -24,6 +24,7 @@ extern crate regex;
 extern crate lazy_static;
 extern crate macaroon;
 extern crate sha1;
+extern crate rand;
 
 pub mod api_entity_crud;
 pub mod api_helpers;
@@ -100,7 +101,9 @@ use diesel::r2d2::ConnectionManager;
 use dotenv::dotenv;
 use iron::middleware::AfterMiddleware;
 use iron::{Request, Response};
-use std::env;
+use std::{env, thread, time};
+use std::process::Command;
+use rand::Rng;
 
 #[cfg(feature = "postgres")]
 embed_migrations!("../migrations/");
@@ -156,22 +159,35 @@ pub fn server() -> Result<api_server::Server> {
     })
 }
 
+/// Generates a server for testing. Calls an external bash script to generate a random postgres
+/// database, which will be unique to this process but common across threads and connections. The
+/// database will automagically get cleaned up (deleted) after 60 seconds.
+/// Currently, start times are staggered by up to 200ms to prevent internal postgres concurrency
+/// errors; if this fails run the tests serially (one at a time), which is slower but more robust.
+/// CI should run tests serially.
 pub fn test_server() -> Result<api_server::Server> {
     dotenv().ok();
-    let database_url = env::var("TEST_DATABASE_URL").expect("TEST_DATABASE_URL must be set");
+    // sleep a bit so we don't have thundering herd collisions, resuliting in
+    // "pg_extension_name_index" or "pg_proc_proname_args_nsp_index" or "pg_type_typname_nsp_index"
+    // duplicate key violations.
+    thread::sleep(time::Duration::from_millis(rand::thread_rng().gen_range(0, 200)));
+    let pg_tmp = Command::new("./tests/pg_tmp.sh")
+        .output()
+        .expect("run ./tests/pg_tmp.sh to get temporary postgres DB");
+    let database_url = String::from_utf8_lossy(&pg_tmp.stdout).to_string();
     env::set_var("DATABASE_URL", database_url);
 
     let mut server = server()?;
     server.auth_confectionary = AuthConfectionary::new_dummy();
     let conn = server.db_pool.get().expect("db_pool error");
 
-    // run migrations; revert latest (dummy data); re-run latest
-    diesel_migrations::run_pending_migrations(&conn).unwrap();
-    diesel_migrations::revert_latest_migration(&conn).unwrap();
+    // run migrations; this is a fresh/bare database
     diesel_migrations::run_pending_migrations(&conn).unwrap();
     Ok(server)
 }
 
+// TODO: move this to bin/fatcatd
+
 /// HTTP header middleware
 header! { (XClacksOverhead, "X-Clacks-Overhead") => [String] }
 
diff --git a/rust/tests/pg_tmp.sh b/rust/tests/pg_tmp.sh
index c7582477..2036a76c 100755
--- a/rust/tests/pg_tmp.sh
+++ b/rust/tests/pg_tmp.sh
@@ -40,6 +40,7 @@ while [ $# -gt 0 ]; do
 done
 
 # bnewbold: hack this in to "make it work" on debian/ubuntu
+# bnewbold: also note, pg_virtualenv could also work, but is ubuntu/debian specific
 export PATH="$PATH:/usr/lib/postgresql/9.6/bin:/usr/lib/postgresql/11/bin"
 initdb -V > /dev/null || exit 1
 PGVER=$(psql -V | awk '{print $NF}')
-- 
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