Fix(test): Compare results to GNU echo

- Added new TestResult type
- Automated 5 testing cases with bash script

mk-outs.sh

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+
+OUTDIR="tests/expected"
+[[ ! -d "$OUTDIR" ]] && mkdir -p "$OUTDIR"
+
+echo "Hello there" > $OUTDIR/hello1.txt
+echo "Hello"  "there" > $OUTDIR/hello2.txt
+echo -n "Hello  there" > $OUTDIR/hello1.n.txt
+echo -n "Hello"  "there" > $OUTDIR/hello2.n.txt

tests/cli.rs

@@ -1,18 +1,43 @@
 use assert_cmd::Command;
 use predicates::prelude::*;
+use std::fs;
+
+type TestResult = Result<(), Box<dyn std::error::Error>>;
 
 #[test]
-fn dies_no_args() {
-    let mut cmd = Command::cargo_bin("echor").expect("cargo binary error");
+fn dies_no_args() -> TestResult {
+    let mut cmd = Command::cargo_bin("echor")?;
 
     cmd.assert()
         .failure()
         .stderr(predicate::str::contains("Usage"));
+
+    Ok(())
+}
+
+fn run(args: &[&str], expected_file: &str) -> TestResult {
+    let expected = fs::read_to_string(expected_file)?;
+    Command::cargo_bin("echor")?
+        .args(args)
+        .assert()
+        .success()
+        .stdout(expected);
+    Ok(())
 }
 
 #[test]
-fn runs() {
-    let mut cmd = Command::cargo_bin("echor").expect("cargo binary error");
-
-    cmd.arg("hello").assert().success();
+fn hello1() -> TestResult {
+    run(&["Hello there"], "tests/expected/hello1.txt")
+}
+#[test]
+fn hello2() -> TestResult {
+    run(&["Hello", "there"], "tests/expected/hello2.txt")
+}
+#[test]
+fn hello1_no_newline() -> TestResult {
+    run(&["Hello  there", "-n"], "tests/expected/hello1.n.txt")
+}
+#[test]
+fn hello2_no_newline() -> TestResult {
+    run(&["-n", "Hello", "there"], "tests/expected/hello2.n.txt")
 }

tests/expected/hello1.n.txt

@@ -0,0 +1 @@
+Hello  there

tests/expected/hello1.txt

@@ -0,0 +1 @@
+Hello there

tests/expected/hello2.n.txt

@@ -0,0 +1 @@
+Hello there

tests/expected/hello2.txt

@@ -0,0 +1 @@
+Hello there