repl: fix tab completion for defined commands

PR-URL: #7364
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

Author: princejwesley

lib/repl.js

@@ -721,11 +721,11 @@ REPLServer.prototype.complete = function(line, callback) {
 
 // REPL commands (e.g. ".break").
 varmatch=null;
-match=line.match(/^\s*(\.\w*)$/);
+match=line.match(/^\s*\.(\w*)$/);
 if(match){
 completionGroups.push(Object.keys(this.commands));
 completeOn=match[1];
-if(match[1].length>1){
+if(match[1].length){
 filter=match[1];
 }
 

test/parallel/test-repl-tab-complete.js

@@ -260,3 +260,10 @@ putIn.run(['.clear']);
 testMe.complete('var log = console.lo',common.mustCall((error,data)=>{
 assert.deepStrictEqual(data,[['console.log'],'console.lo']);
 }));
+
+// tab completion for defined commands
+putIn.run(['.clear']);
+
+testMe.complete('.b',common.mustCall((error,data)=>{
+assert.deepStrictEqual(data,[['break'],'b']);
+}));