lib: explicit util.promisify() compat

index.js

@@ -4,6 +4,7 @@
 var stream = require('readable-stream');
 var assert = require('assert');
 var fs = require('fs');
+var util = require('util');
 
 // node-pre-gyp magic
 var nodePreGyp = require('node-pre-gyp');
@@ -421,6 +422,11 @@ exports.decompress = function(string, opt, on_finish) {
   return singleStringCoding(stream, string, on_finish);
 };
 
+if (util.promisify) {
+  exports.compress[util.promisify.custom] = exports.compress;
+  exports.decompress[util.promisify.custom] = exports.decompress;
+}
+
 exports.isXZ = function(buf) {
   return buf && buf.length >= 6 &&
          buf[0] === 0xfd &&

test/compat.js

@@ -2,6 +2,7 @@
 
 var assert = require('assert');
 var fs = require('fs');
+var util = require('util');
 var helpers = require('./helpers.js');
 
 var lzma = require('../');
@@ -140,3 +141,31 @@ describe('lzma.compress()/decompress() with ES6 Promises', function() {
     });
   });
 });
+
+describe('lzma.compress()/decompress() with util.promisify()', function() {
+  var majorVersion = process.version.match(/^v(\d+)\./);
+  if (majorVersion && +majorVersion[1] < 8) {
+    return;
+  }
+
+  var compress = util.promisify(lzma.compress);
+  var decompress = util.promisify(lzma.decompress);
+
+  it('can round-trip', function() {
+    return compress('Bananas', 5).then(function(result) {
+      assert.equal(result.toString('base64'), BananasCompressed);
+      return decompress(result);
+    }).then(function(result) {
+      assert.ok(Buffer.isBuffer(result));
+      assert.equal(result.toString(), 'Bananas');
+    });
+  });
+
+  it('fails for invalid input', function() {
+    return decompress('ABC').then(function(result) {
+      assert.ok(false); // never get here due to error
+    }).catch(function(err) {
+      assert.ok(err);
+    });
+  });
+});