Disabled salt provision required install_type check on Windows where option is not supported. Added test case for salt provisioner config changes.

plugins/provisioners/salt/config.rb

@@ -177,8 +177,11 @@ module VagrantPlugins
           errors << I18n.t("vagrant.provisioners.salt.python_version")
         end
 
-        if @version && !@install_type
-          errors << I18n.t("vagrant.provisioners.salt.version_type_missing")
+        # install_type is not supported in a Windows environment
+        if machine.config.vm.communicator != :winrm
+          if @version && !@install_type
+            errors << I18n.t("vagrant.provisioners.salt.version_type_missing")
+          end
         end
 
         return {"salt provisioner" => errors}

test/unit/plugins/provisioners/salt/config_test.rb

@@ -156,5 +156,25 @@ describe VagrantPlugins::Salt::Config do
         expect(result[error_key]).to_not be_empty
       end
     end
+
+    context "version" do
+      it "is valid if is set without install_type on Windows" do
+        allow(machine.config.vm).to receive(:communicator).and_return(:winrm)
+
+        subject.version = "2018.3.3"
+        subject.finalize!
+
+        result = subject.validate(machine)
+        expect(result[error_key]).to be_empty
+      end
+
+      it "is invalid if is set without install_type on Linux" do
+        subject.version = "2018.3.3"
+        subject.finalize!
+
+        result = subject.validate(machine)
+        expect(result[error_key]).to_not be_empty
+      end
+    end
   end
 end