Rust learning: lessons, notes, and exercise crates

tasks/tests/spec.rs

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+// The specification, as executable tests. Do not edit this file — make it pass.
+// Copy to: tasks/tests/spec.rs
+// Run with: cargo test
+
+use tasks::command::Command;
+use tasks::store::Store;
+use tasks::task::{Priority, Status, Task};
+
+/// Helper: build an argument list the way main() would pass it in
+/// (program name already stripped).
+fn args(list: &[&str]) -> Vec<String> {
+    list.iter().map(|s| s.to_string()).collect()
+}
+
+// ---------- task.rs ----------
+
+#[test]
+fn new_task_starts_as_todo() {
+    let task = Task::new(1, "write the spec", Priority::High);
+    assert_eq!(task.id, 1);
+    assert_eq!(task.title, "write the spec");
+    assert_eq!(task.status, Status::Todo);
+    assert_eq!(task.priority, Priority::High);
+}
+
+#[test]
+fn status_labels() {
+    assert_eq!(Status::Todo.label(), "todo");
+    assert_eq!(Status::InProgress.label(), "in-progress");
+    assert_eq!(Status::Done.label(), "done");
+}
+
+#[test]
+fn priority_labels() {
+    assert_eq!(Priority::Low.label(), "low");
+    assert_eq!(Priority::Medium.label(), "medium");
+    assert_eq!(Priority::High.label(), "high");
+}
+
+#[test]
+fn priority_parses_known_words_only() {
+    assert_eq!(Priority::parse("low"), Some(Priority::Low));
+    assert_eq!(Priority::parse("medium"), Some(Priority::Medium));
+    assert_eq!(Priority::parse("high"), Some(Priority::High));
+    assert_eq!(Priority::parse("urgent"), None);
+    assert_eq!(Priority::parse(""), None);
+}
+
+// ---------- command.rs ----------
+
+#[test]
+fn parses_add_with_default_priority() {
+    let command = Command::parse(&args(&["add", "buy milk"])).unwrap();
+    assert_eq!(
+        command,
+        Command::Add {
+            title: "buy milk".to_string(),
+            priority: Priority::Medium,
+        }
+    );
+}
+
+#[test]
+fn parses_add_with_explicit_priority() {
+    let command = Command::parse(&args(&["add", "ship it", "high"])).unwrap();
+    assert_eq!(
+        command,
+        Command::Add {
+            title: "ship it".to_string(),
+            priority: Priority::High,
+        }
+    );
+}
+
+#[test]
+fn parses_list_done_and_remove() {
+    assert_eq!(Command::parse(&args(&["list"])).unwrap(), Command::List);
+    assert_eq!(
+        Command::parse(&args(&["done", "7"])).unwrap(),
+        Command::Done { id: 7 }
+    );
+    assert_eq!(
+        Command::parse(&args(&["remove", "12"])).unwrap(),
+        Command::Remove { id: 12 }
+    );
+}
+
+#[test]
+fn rejects_bad_input() {
+    assert!(Command::parse(&args(&[])).is_err(), "no command at all");
+    assert!(Command::parse(&args(&["fly"])).is_err(), "unknown command");
+    assert!(Command::parse(&args(&["add"])).is_err(), "add with no title");
+    assert!(
+        Command::parse(&args(&["add", "x", "urgent"])).is_err(),
+        "unknown priority word"
+    );
+    assert!(Command::parse(&args(&["done"])).is_err(), "done with no id");
+    assert!(
+        Command::parse(&args(&["done", "abc"])).is_err(),
+        "id is not a number"
+    );
+    assert!(
+        Command::parse(&args(&["remove", "-1"])).is_err(),
+        "negative id is not a u32"
+    );
+}
+
+// ---------- store.rs ----------
+
+#[test]
+fn add_returns_ids_starting_at_one() {
+    let mut store = Store::new();
+    assert_eq!(store.add("first", Priority::Low), 1);
+    assert_eq!(store.add("second", Priority::Low), 2);
+    assert_eq!(store.add("third", Priority::Low), 3);
+}
+
+#[test]
+fn tasks_come_back_in_insertion_order() {
+    let mut store = Store::new();
+    store.add("first", Priority::Low);
+    store.add("second", Priority::High);
+
+    let listed = store.tasks();
+    assert_eq!(listed.len(), 2);
+    assert_eq!(listed[0].title, "first");
+    assert_eq!(listed[1].title, "second");
+}
+
+#[test]
+fn new_store_is_empty() {
+    let store = Store::new();
+    assert!(store.tasks().is_empty());
+}
+
+#[test]
+fn complete_sets_status_to_done() {
+    let mut store = Store::new();
+    let id = store.add("do the thing", Priority::Medium);
+
+    assert_eq!(store.find(id).unwrap().status, Status::Todo);
+    assert!(store.complete(id).is_ok());
+    assert_eq!(store.find(id).unwrap().status, Status::Done);
+}
+
+#[test]
+fn complete_unknown_id_is_an_error() {
+    let mut store = Store::new();
+    store.add("only task", Priority::Low);
+    assert!(store.complete(99).is_err());
+}
+
+#[test]
+fn remove_deletes_only_that_task() {
+    let mut store = Store::new();
+    let first = store.add("first", Priority::Low);
+    let second = store.add("second", Priority::Low);
+
+    assert!(store.remove(first).is_ok());
+    assert_eq!(store.tasks().len(), 1);
+    assert!(store.find(first).is_none());
+    assert!(store.find(second).is_some());
+}
+
+#[test]
+fn remove_unknown_id_is_an_error() {
+    let mut store = Store::new();
+    assert!(store.remove(1).is_err());
+}
+
+#[test]
+fn find_returns_none_for_missing_id() {
+    let store = Store::new();
+    assert!(store.find(1).is_none());
+}
+
+#[test]
+fn ids_are_not_reused_after_remove() {
+    let mut store = Store::new();
+    let first = store.add("first", Priority::Low);
+    store.remove(first).unwrap();
+    let second = store.add("second", Priority::Low);
+    assert_ne!(first, second, "a removed id must not be handed out again");
+}