test: cover the store and the exit codes before moving any of it

tests/output_io.rs

@@ -0,0 +1,99 @@
+// what a command reports and how it exits, including when the write fails.
+mod support;
+
+use std::fs;
+use support::Case;
+
+#[test]
+fn findings_are_reported_through_the_exit_code() {
+    let case = Case::new("findings");
+    case.write("loose.txt", b"x\n");
+
+    case.ahab(&["link", "check"]).ok();
+    case.ahab(&["link", "check", "--exit-code"]).code_is(4);
+}
+
+#[test]
+fn an_argument_error_exits_two() {
+    let case = Case::new("usage");
+
+    case.ahab(&["link", "restore"]).code_is(2);
+    case.ahab(&["link", "restore", "--all", "some/path"])
+        .code_is(2);
+    case.ahab(&["postgres", "dump", "-F", "directory", "-z", "d"])
+        .code_is(2);
+    case.ahab(&["nonsense"]).code_is(2);
+}
+
+#[test]
+fn a_write_that_cannot_be_delivered_is_a_failure_rather_than_a_success() {
+    let case = Case::new("devfull");
+    for n in 0..200 {
+        case.write(&format!("file-{n}.txt"), b"x\n");
+    }
+
+    // /dev/full accepts the open and fails the write. exiting 0 there would
+    // report a listing that was never delivered
+    let Ok(full) = fs::File::create("/dev/full") else {
+        eprintln!("skipped: this system has no /dev/full to fail a write against");
+        return;
+    };
+
+    let out = std::process::Command::new(env!("CARGO_BIN_EXE_ahab"))
+        .current_dir(&case.repo)
+        .env("XDG_DATA_HOME", case.repo.join("../xdg"))
+        .args(["link", "check", "--exit-code", "--porcelain"])
+        .stdout(full)
+        .output()
+        .expect("running ahab");
+
+    assert_eq!(out.status.code(), Some(1), "{:?}", out.status);
+    assert!(
+        String::from_utf8_lossy(&out.stderr).contains("writing to stdout failed"),
+        "{}",
+        String::from_utf8_lossy(&out.stderr)
+    );
+}
+
+#[test]
+fn every_named_path_is_moved_even_when_the_reader_leaves() {
+    let case = Case::new("partial");
+    for name in ["a.env", "b.env", "c.env"] {
+        case.write(name, b"x\n");
+    }
+    case.gitignore("a.env\nb.env\nc.env\n");
+
+    // a closed stdout must stop the writing, not the moving: the command had
+    // planned to move all three and reported success for doing so
+    let run = case.ahab(&["link", "add", "a.env", "b.env", "c.env"]);
+    run.ok();
+
+    for name in ["a.env", "b.env", "c.env"] {
+        assert!(case.is_symlink(name), "{name} was left behind");
+    }
+}
+
+#[test]
+fn quiet_keeps_the_reason_a_path_failed() {
+    let case = Case::new("quiet");
+    case.write("ok.env", b"x\n");
+    case.gitignore("ok.env\n");
+
+    let run = case.ahab(&["-q", "link", "add", "ok.env", "missing.env"]);
+    run.failed()
+        .says("1 of 2 paths failed")
+        // the line saying *which* and *why* is a result, not progress
+        .says("missing.env");
+}
+
+#[test]
+fn a_dry_run_changes_nothing_on_disk() {
+    let case = Case::new("dryrun");
+    case.write(".env", b"SECRET=1\n");
+    case.gitignore(".env\n");
+
+    case.ahab(&["--dry-run", "link", "add", ".env"]).ok();
+
+    assert!(!case.is_symlink(".env"));
+    assert!(!case.store.join(".env").exists());
+}