[pull] master from DefinitelyTyped:master

types/w3c-web-usb/index.d.ts

@@ -39,7 +39,7 @@ interface USBConnectionEventInit extends EventInit {
 
 declare class USBConfiguration {
     readonly configurationValue: number;
-    readonly configurationName?: string | undefined;
+    readonly configurationName: string | null;
     readonly interfaces: USBInterface[];
 }
 
@@ -57,7 +57,7 @@ declare class USBAlternateInterface {
     readonly interfaceClass: number;
     readonly interfaceSubclass: number;
     readonly interfaceProtocol: number;
-    readonly interfaceName?: string | undefined;
+    readonly interfaceName: string | null;
     readonly endpoints: USBEndpoint[];
 }
 
@@ -140,10 +140,10 @@ declare class USBDevice {
     readonly deviceVersionMajor: number;
     readonly deviceVersionMinor: number;
     readonly deviceVersionSubminor: number;
-    readonly manufacturerName?: string | undefined;
-    readonly productName?: string | undefined;
-    readonly serialNumber?: string | undefined;
-    readonly configuration?: USBConfiguration | undefined;
+    readonly manufacturerName: string | null;
+    readonly productName: string | null;
+    readonly serialNumber: string | null;
+    readonly configuration: USBConfiguration | null;
     readonly configurations: USBConfiguration[];
     readonly opened: boolean;
     open(): Promise<void>;

types/w3c-web-usb/w3c-web-usb-tests.ts

@@ -87,3 +87,30 @@ async function handleConnectedDevice(device: USBDevice) {
         }
     }
 }
+
+function testNullVsUndefined(device: USBDevice) {
+    // There are certain properties that are nullable, meaning they return null
+    // rather than undefined. These constructs test that this is the case.
+
+    if (device.manufacturerName !== null) {
+        device.manufacturerName.length;
+    }
+
+    if (device.productName !== null) {
+        device.productName.length;
+    }
+
+    if (device.serialNumber !== null) {
+        device.serialNumber.length;
+    }
+
+    if (device.configuration !== null) {
+        if (device.configuration.configurationName !== null) {
+            device.configuration.configurationName.length;
+        }
+
+        if (device.configuration.interfaces[0].alternate.interfaceName !== null) {
+            device.configuration.interfaces[0].alternate.interfaceName.length;
+        }
+    }
+}