Fix quick-pick initiated by the plugins not displaying with a single …

…item

Fixes #6050

- fixes issue where `quick-pick` which were initiated by the plugins was
not displayed when it only contains a single item. The fix is to include
a new flag `runIfSingle` which is used to determine if the quick-pick
should display or execute the item.
- The default value for `runIfSingle` is set to `true`.
- The `plugin-ext` sets the `runIfSingle` to `false` so it always displays
the quick-pick regardless if an single item is present. This behavior is aligned
with previous versions of Theia and VSCode.

Signed-off-by: Vincent Fugnitto <vincent.fugnitto@ericsson.com>

packages/core/src/browser/quick-open/quick-pick-service-impl.ts

@@ -38,7 +38,9 @@ export class QuickPickServiceImpl implements QuickPickService {
     async show(elements: (string | QuickPickItem<Object>)[], options?: QuickPickOptions): Promise<Object | undefined> {
         return new Promise<Object | undefined>(resolve => {
             this.items = this.toItems(elements, resolve);
-            if (this.items.length === 1) {
+            // Set `runIfSingle` to the value passed through options, else default to true.
+            const runIfSingle: boolean = (options && options.runIfSingle !== undefined) ? options.runIfSingle : true;
+            if (runIfSingle && this.items.length === 1) {
                 this.items[0].run(QuickOpenMode.OPEN);
                 return;
             }

packages/core/src/common/quick-pick-service.ts

@@ -77,6 +77,12 @@ export interface QuickPickOptions {
      * The prefill value.
      */
     value?: string;
+
+    /**
+     * Determines if the quick pick with a single item should
+     * execute the item instead of displaying.
+     */
+    runIfSingle?: boolean;
 }
 
 export const quickPickServicePath = '/services/quickPick';

packages/plugin-ext/src/main/browser/quick-open-main.ts

@@ -292,7 +292,8 @@ export class QuickOpenMainImpl implements QuickOpenMain, QuickOpenModel {
             title: options.title,
             totalSteps: options.totalSteps,
             ignoreFocusOut: options.ignoreFocusOut,
-            value: options.value
+            value: options.value,
+            runIfSingle: false,
         });
 
         const disposableListeners = new DisposableCollection();