Use prefixLength (#189)

The setting was not being sent through.
Also added a test confirm the behavior and prevent regressions.

Author: Bruno Bernardino

bin/concurrently.js

@@ -154,6 +154,7 @@ concurrently(args._.map((command, index) => {
         : (args.killOthersOnFail ? ['failure'] : []),
     raw: args.raw,
     prefix: args.prefix,
+    prefixLength: args.prefixLength,
     restartDelay: args.restartAfter,
     restartTries: args.restartTries,
     successCondition: args.success,

bin/concurrently.spec.js

@@ -207,6 +207,26 @@ describe('--prefix', () => {
     });
 });
 
+describe('--prefix-length', () => {
+    it('is alised to -l', done => {
+        const child = run('-p command -l 5 "echo foo" "echo bar"');
+        child.log.pipe(buffer(child.close)).subscribe(lines => {
+            expect(lines).toContainEqual(expect.stringContaining('[ec..o] foo'));
+            expect(lines).toContainEqual(expect.stringContaining('[ec..r] bar'));
+            done();
+        }, done);
+    });
+
+    it('specifies custom prefix length', done => {
+        const child = run('--prefix command --prefix-length 5 "echo foo" "echo bar"');
+        child.log.pipe(buffer(child.close)).subscribe(lines => {
+            expect(lines).toContainEqual(expect.stringContaining('[ec..o] foo'));
+            expect(lines).toContainEqual(expect.stringContaining('[ec..r] bar'));
+            done();
+        }, done);
+    });
+});
+
 describe('--restart-tries', () => {
     it('changes how many times a command will restart', done => {
         const child = run('--restart-tries 1 "exit 1"');