Echo stdout (#677)

nfischer · nfischer · commit 18034486a51a · 2017-06-06T21:10:27.000-07:00
* Add newline to output of echo (#557) * Add newline to output of echo * Add test * Throw an error if the options string does not start with '-' (#615) * Throw an error if the options string does not start with '-' * Add test * Change message grammar * Add -n option to echo * Fix null argument issue * Add -n tests * Add documentation * Add -en escaped character test * Add function to parse options for echo * Use parseOptions to parse echo options * Simplify control flow * parseOptions throws now * Allow null to be echoed * Prevent echo stderr on unrecognized option * Add test to check stderr of returned value * Use consistent variable name * Change test message, leave TODO about console output
diff --git a/README.md b/README.md
@@ -259,12 +259,14 @@ See also: pushd, popd
 Available options:
 
 + `-e`: interpret backslash escapes (default)
++ `-n`: remove trailing newline from output
 
 Examples:
 
 ```javascript
 echo('hello world');
 var str = echo('hello world');
+echo('-n', 'no newline at end');
 ```
 
 Prints string to stdout, and returns string with additional utility methods
diff --git a/src/common.js b/src/common.js
@@ -172,6 +172,8 @@ exports.getUserHome = getUserHome;
 //   parseOptions('-a', {'a':'alice', 'b':'bob'});
 // Returns {'reference': 'string-value', 'bob': false} when passed two dictionaries of the form:
 //   parseOptions({'-r': 'string-value'}, {'r':'reference', 'b':'bob'});
+// Throws an error when passed a string that does not start with '-':
+//   parseOptions('a', {'a':'alice'}); // throws
 function parseOptions(opt, map, errorOptions) {
   // Validate input
   if (typeof opt !== 'string' && !isObject(opt)) {
diff --git a/src/echo.js b/src/echo.js
@@ -1,3 +1,5 @@
+var format = require('util').format;
+
 var common = require('./common');
 
 common.register('echo', _echo, {
@@ -9,26 +11,52 @@ common.register('echo', _echo, {
 //@ Available options:
 //@
 //@ + `-e`: interpret backslash escapes (default)
+//@ + `-n`: remove trailing newline from output
 //@
 //@ Examples:
 //@
 //@ ```javascript
 //@ echo('hello world');
 //@ var str = echo('hello world');
+//@ echo('-n', 'no newline at end');
 //@ ```
 //@
 //@ Prints string to stdout, and returns string with additional utility methods
 //@ like `.to()`.
-function _echo(opts, messages) {
+function _echo(opts) {
   // allow strings starting with '-', see issue #20
-  messages = [].slice.call(arguments, opts ? 0 : 1);
+  var messages = [].slice.call(arguments, opts ? 0 : 1);
+  var options = {};
+
+  // If the first argument starts with '-', parse it as options string.
+  // If parseOptions throws, it wasn't an options string.
+  try {
+    options = common.parseOptions(messages[0], {
+      'e': 'escapes',
+      'n': 'no_newline'
+    }, {
+      silent: true
+    });
 
-  if (messages[0] === '-e') {
-    // ignore -e
-    messages.shift();
+    // Allow null to be echoed
+    if (messages[0]) {
+      messages.shift();
+    }
+  } catch (_) {
+    // Clear out error if an error occurred
+    common.state.error = null;
   }
 
-  console.log.apply(console, messages);
-  return messages.join(' ') + '\n';
+  var output = format.apply(null, messages);
+
+  // Add newline if -n is not passed.
+  if (!options.no_newline) {
+    output += '\n';
+  }
+
+  process.stdout.write(output);
+
+  return output;
 }
+
 module.exports = _echo;
diff --git a/test/common.js b/test/common.js
@@ -269,6 +269,12 @@ test('common.parseOptions using an object to hold options', t => {
   t.false(result.reverse);
 });
 
+test('common.parseOptions throws when passed a string not starting with "-"', t => {
+  t.throws(() => {
+    common.parseOptions('a', { '-a': 'throws' });
+  }, 'Options string must start with "-"');
+});
+
 test('Some basic tests on the ShellString type', t => {
   const result = shell.ShellString('foo');
   t.is(result.toString(), 'foo');
diff --git a/test/echo.js b/test/echo.js
@@ -79,3 +79,60 @@ test.cb('piping to a file', t => {
     t.end();
   });
 });
+
+test.cb('-n option', t => {
+  const script = "require('../global.js'); echo('-n', 'message');";
+  utils.runScript(script, (err, stdout) => {
+    t.falsy(err);
+    t.is(stdout, 'message');
+    t.end();
+  });
+});
+
+test.cb('-ne option', t => {
+  const script = "require('../global.js'); echo('-ne', 'message');";
+  utils.runScript(script, (err, stdout) => {
+    t.falsy(err);
+    t.is(stdout, 'message');
+    t.end();
+  });
+});
+
+test.cb('-en option', t => {
+  const script = "require('../global.js'); echo('-en', 'message');";
+  utils.runScript(script, (err, stdout) => {
+    t.falsy(err);
+    t.is(stdout, 'message');
+    t.end();
+  });
+});
+
+test.cb('-en option with escaped characters', t => {
+  const script = "require('../global.js'); echo('-en', '\\tmessage\\n');";
+  utils.runScript(script, (err, stdout) => {
+    t.falsy(err);
+    t.is(stdout, '\tmessage\n');
+    t.end();
+  });
+});
+
+test.cb('piping to a file with -n', t => {
+  // see issue #476
+  shell.mkdir(t.context.tmp);
+  const tmp = `${t.context.tmp}/echo.txt`;
+  const script = `require('../global.js'); echo('-n', 'A').toEnd('${tmp}'); echo('-n', 'B').toEnd('${tmp}');`;
+  utils.runScript(script, (err, stdout) => {
+    const result = shell.cat(tmp);
+    t.falsy(err);
+    t.is(stdout, 'AB');
+    t.is(result.toString(), 'AB');
+    t.end();
+  });
+});
+
+test('stderr with unrecognized options is empty', t => {
+  // TODO: console output here needs to be muted
+  const result = shell.echo('-asdf');
+  t.falsy(result.stderr);
+  t.is(result.stdout, '-asdf\n');
+});
