adding getVersion w/ promise

Author: Almenon

index.ts

@@ -4,6 +4,7 @@ import {EOL as newline, tmpdir} from 'os';
 import {join, sep} from 'path'
 import {Readable,Writable} from 'stream'
 import { writeFile, writeFileSync } from 'fs';
+import { promisify } from 'util';
 
 function toArray<T>(source?:T|T[]):T[] {
     if (typeof source === 'undefined' || source === null) {
@@ -290,6 +291,12 @@ export class PythonShell extends EventEmitter{
         return PythonShell.run(filePath, options, callback);
     };
 
+    static getVersion(pythonPath?:string){
+        if(!pythonPath) pythonPath = this.defaultPythonPath
+        const execPromise = promisify(exec)
+        return execPromise(pythonPath + " --version");
+    }
+
     static getVersionSync(pythonPath?:string){
         if(!pythonPath) pythonPath = this.defaultPythonPath
         return execSync(pythonPath + " --version").toString()

test/test-python-shell.ts

@@ -78,6 +78,17 @@ describe('PythonShell', function () {
         })
     })
 
+    describe("#getVersion", function(){
+        it('should return a string', function(done){
+            PythonShell.getVersion().then((out)=>{
+                const version = out.stdout
+                version.should.be.a.String();
+                version.length.should.be.greaterThan(0)
+                done()
+            })
+        })
+    })
+
     describe("#getVersionSync", function(){
         it('should return a string', function(){
             const version = PythonShell.getVersionSync()