use assert_cmd::prelude::*; //Add methods on commands use predicates::prelude::*; //Used for writing assertions use std::process::Command; //Run programs use assert_fs::prelude::*; #[test] fn file_doesnt_exist() -> Result<(), Box>{ let mut cmd = Command::cargo_bin("grrs")?; cmd.arg("foobar").arg("test/file/doesnt/exist"); cmd.assert() .failure() .stderr(predicates::str::contains("Could not read file")); Ok(()) } #[test] fn find_content_in_file() -> Result<(), Box>{ let file = assert_fs::NamedTempFile::new("sample.txt")?; file.write_str("A test\nActual content\nMore content\nAnother test")?; let mut cmd = Command::cargo_bin("grrs")?; cmd.arg("test").arg(file.path()); cmd.assert() .success() .stdout(predicate::str::contains("test\nAnother test")); Ok(()) } #[test] fn empty_string_pattern() -> Result<(), Box>{ let mut cmd = Command::cargo_bin("grrs")?; cmd.arg("").arg("this/will/not/run.txt"); cmd.assert() .failure() .stderr(predicates::str::contains("Could not read file")); Ok(()) }