This is a demo showing how cargo pollutes environment variables and break a test case.
On linux, cargo leaks env variables such as SSL_CERT_FILE and SSL_CERT_DIR.
openssl will loads certificates from
SSL_CERT_FILE is this env var is set.
Thus if a program(e.g., unittest) depends on openssl, cargo build && ./target/debug/bin-name may work very fine, but cargo run may time out,
because loading certificates takes several dozen milliseconds(~ 30ms to 70ms).
cargo run in this repo shows the env vars a program sees and the time it takes
calling openssl::ssl::SslConnector::builder().
On linux:
cargo run
SSL_CERT_DIR: /usr/lib/ssl/certs
SSL_CERT_FILE: /usr/lib/ssl/certs/ca-certificates.crt
...
=== : 66.382982ms
On my m1 mac:
cargo run
...
=== : 9.23432ms