argv: Add support for boolean flags when equal sign is used

lib/stores/argv.mjs

@@ -52,6 +52,8 @@ Argv.prototype.load = function () {
         let equalSignIndex = key.indexOf('=')
         if (equalSignIndex > 0) {
           this.set(key.slice(0, equalSignIndex), key.slice(equalSignIndex + 1))
+        } else {
+          this.set(key, true)
         }
       } else if (args[i + 1] && !args[i + 1].startsWith(this.prefix)) {
         this.set(key, args[i + 1])

test/stores/argv.test.mjs

@@ -140,6 +140,25 @@ t.describe('#load()', () => {
       testety: 'hello',
     })
   })
+  
+  t.test('equal sign should support boolean values', function() {
+    process.argv = ['bla', 'bla',
+    '--booleanone',
+    '--foobar=123',
+    '--testety=hello',
+    '--booleantwo',
+    ]
+    let store = new Nconf.Argv({ useEqualsign: true })
+    store.load()
+    assert.strictEqual(store.get('booleanone'), true)
+    assert.strictEqual(store.get('booleantwo'), true)
+    assert.deepStrictEqual(store.get(), {
+      foobar: '123',
+      testety: 'hello',
+      booleanone: true,
+      booleantwo: true,
+    })
+  })
 
   t.test('should be smart with the usage of equal sign', function() {
     process.argv = ['bla', 'bla',