test: Add test codebase for shell completions

src/cargo/util/command_prelude.rs

@@ -22,6 +22,7 @@ use cargo_util_schemas::manifest::RegistryName;
 use cargo_util_schemas::manifest::StringOrVec;
 use clap::builder::UnknownArgumentValueParser;
 use home::cargo_home_with_cwd;
+use itertools::Itertools;
 use semver::Version;
 use std::collections::HashMap;
 use std::ffi::{OsStr, OsString};
@@ -1104,14 +1105,15 @@ pub fn get_registry_candidates(
     {
         Ok(registries
             .keys()
+            .sorted()
             .map(|name| clap_complete::CompletionCandidate::new(name.to_owned()))
             .collect())
     } else {
         Ok(vec![])
     }
 }
 
-fn get_example_candidates(cwd: Option<PathBuf>) -> Vec<clap_complete::CompletionCandidate> {
+pub fn get_example_candidates(cwd: Option<PathBuf>) -> Vec<clap_complete::CompletionCandidate> {
     get_targets_from_metadata(cwd)
         .unwrap_or_default()
         .into_iter()

tests/testsuite/shell_completions/mod.rs

@@ -3,6 +3,20 @@ use std::path::PathBuf;
 use cargo::util::command_prelude::*;
 use cargo_test_support::cargo_test;
 
+#[cargo_test]
+fn test_get_example_candidates() {
+    let current_dir = std::env::current_dir().expect("Failed to get current directory");
+    let cwd = PathBuf::from(file!()).parent().unwrap().join("template");
+    let cwd = current_dir.join(cwd);
+
+    let expected = snapbox::str![
+        "example1
+example2"
+    ];
+    let actual = print_candidates(get_example_candidates(Some(cwd)));
+    snapbox::assert_data_eq!(actual, expected);
+}
+
 #[cargo_test]
 fn test_get_registry_candidates() {
     let current_dir = std::env::current_dir().expect("Failed to get current directory");

tests/testsuite/shell_completions/template/Cargo.toml

@@ -0,0 +1,16 @@
+[workspace]
+resolver = "2"
+
+[workspace.package]
+rust-version = "1.81"
+edition = "2021"
+
+[package]
+name = "template"
+version = "0.1.0"
+edition.workspace = true
+rust-version = "1.81"
+
+[lib]
+name = "template"
+path = "src/lib.rs"

tests/testsuite/shell_completions/template/examples/example1.rs

@@ -0,0 +1 @@
+

tests/testsuite/shell_completions/template/examples/example2.rs

@@ -0,0 +1 @@
+

tests/testsuite/shell_completions/template/src/lib.rs

@@ -0,0 +1 @@
+