Use terminal width for CLI wrapping

I was using a larger-than-usual terminal window and noticed the output was
still wrapped to 78 characters.

This uses process.stdout.columns if available to set the CLI wrap value.
(minus two pixels to preserve a similar padding effect as using 78 over 80).

src/cli.js

@@ -4,6 +4,19 @@ import { singleLineString } from 'utils';
 import { version } from 'json!../package';
 
 
+export function _terminalWidth(_process=process) {
+  if (_process && _process.stdout && _process.stdout.columns > 0) {
+    var width = _process.stdout.columns - 2;
+    // Terminals less than ten pixels wide seem silly.
+    if (width < 10) {
+      width = 10;
+    }
+
+    return width;
+  } else {
+    return 78;
+  }
+}
 
 export default argv
   .usage('Usage: ./$0 [options] addon-package \n\n' +
@@ -81,4 +94,4 @@ export default argv
   .demand(1)
   .help('help')
   .alias('h', 'help')
-  .wrap(78);
+  .wrap(_terminalWidth());

tests/test.cli.js

@@ -1,4 +1,4 @@
-import { default as cli_ } from 'cli';
+import { default as cli_, _terminalWidth } from 'cli';
 
 
 var cli;
@@ -69,4 +69,34 @@ describe('Basic CLI tests', function() {
         'Invalid values:\n  Argument: output, Given: "false"'));
   });
 
+  it('should use 78 as a width if process.stdout.columns is undefined', () => {
+    var fakeProcess = null;
+    assert.equal(_terminalWidth(fakeProcess), 78);
+    fakeProcess = {stdout: null};
+    assert.equal(_terminalWidth(fakeProcess), 78);
+    fakeProcess = {stdout: {columns: null}};
+    assert.equal(_terminalWidth(fakeProcess), 78);
+  });
+
+  it('should always use a positive terminal width', () => {
+    var fakeProcess = {stdout: {columns: 1}};
+    assert.equal(_terminalWidth(fakeProcess), 10);
+  });
+
+  it('should not use a width under 10 columns', () => {
+    var fakeProcess = {stdout: {columns: 12}};
+    assert.equal(_terminalWidth(fakeProcess), 10);
+
+    fakeProcess = {stdout: {columns: 11}};
+    assert.equal(_terminalWidth(fakeProcess), 10);
+
+    fakeProcess = {stdout: {columns: 79}};
+    assert.equal(_terminalWidth(fakeProcess), 77);
+  });
+
+  it('should use a terminal width of $COLUMNS - 2', () => {
+    var fakeProcess = {stdout: {columns: 170}};
+    assert.equal(_terminalWidth(fakeProcess), 168);
+  });
+
 });