test: add the CLI argument case

Author: 0xPoe

tests/testsuite/install.rs

@@ -536,6 +536,25 @@ fn relative_install_location_without_trailing_slash() {
     // NOTE: the install location is relative to the CWD, not the config file
     assert_has_not_installed_exe(&root_t1, "foo");
     assert_has_installed_exe(&project_t1, "foo");
+
+    // Verify that using the --root CLI argument does not produce the deprecation warning.
+    // Remove the config file and previous install from the test above.
+    fs::remove_file(root.join(".cargo/config.toml")).unwrap();
+    fs::remove_dir_all(&project_t1).unwrap();
+    cargo_process("install --path . --root")
+        .arg("t1")
+        .cwd(p.root())
+        .with_stderr_data(str![[r#"
+[INSTALLING] foo v0.0.1 ([ROOT]/foo)
+[FINISHED] `release` profile [optimized] target(s) in [ELAPSED]s
+[INSTALLING] [ROOT]/foo/t1/bin/foo[EXE]
+[INSTALLED] package `foo v0.0.1 ([ROOT]/foo)` (executable `foo[EXE]`)
+[WARNING] be sure to add `[ROOT]/foo/t1/bin` to your PATH to be able to run the installed binaries
+
+"#]])
+        .run();
+    assert_has_not_installed_exe(&root_t1, "foo");
+    assert_has_installed_exe(&project_t1, "foo");
 }
 
 #[cargo_test]