Cache debug config selection when using run and debug. (#16934)

* Cache debug config seletion when using run and debug.

* Add tests, and news item

news/1 Enhancements/16934.md

@@ -0,0 +1 @@
+Cache last selection for debug configuration when debugging without launch.json.

src/client/debugger/extension/configuration/debugConfigurationService.ts

@@ -4,6 +4,7 @@
 'use strict';
 
 import { inject, injectable, named } from 'inversify';
+import { cloneDeep } from 'lodash';
 import { CancellationToken, DebugConfiguration, QuickPickItem, WorkspaceFolder } from 'vscode';
 import { DebugConfigStrings } from '../../../common/utils/localize';
 import {
@@ -18,6 +19,7 @@ import { IDebugConfigurationProviderFactory, IDebugConfigurationResolver } from
 
 @injectable()
 export class PythonDebugConfigurationService implements IDebugConfigurationService {
+    private cacheDebugConfig: DebugConfiguration | undefined = undefined;
     constructor(
         @inject(IDebugConfigurationResolver)
         @named('attach')
@@ -62,6 +64,9 @@ export class PythonDebugConfigurationService implements IDebugConfigurationServi
         } else if (debugConfiguration.request === 'test') {
             throw Error("Please use the command 'Python: Debug All Tests'");
         } else {
+            if (this.cacheDebugConfig) {
+                debugConfiguration = cloneDeep(this.cacheDebugConfig);
+            }
             if (Object.keys(debugConfiguration).length === 0) {
                 const configs = await this.provideDebugConfigurations(folder, token);
                 if (configs === undefined) {
@@ -70,6 +75,7 @@ export class PythonDebugConfigurationService implements IDebugConfigurationServi
                 if (Array.isArray(configs) && configs.length === 1) {
                     debugConfiguration = configs[0];
                 }
+                this.cacheDebugConfig = cloneDeep(debugConfiguration);
             }
             return this.launchResolver.resolveDebugConfiguration(
                 folder,

src/test/debugger/extension/configuration/debugConfigurationService.unit.test.ts

@@ -151,4 +151,35 @@ suite('Debugging - Configuration Service', () => {
 
         expect(config).to.equal(undefined, `Config should be undefined`);
     });
+    test('Use cached debug configuration', async () => {
+        const folder = { name: '1', index: 0, uri: Uri.parse('1234') };
+        const expectedConfig = {
+            name: 'File',
+            type: 'python',
+            request: 'launch',
+            program: '${file}',
+            console: 'integratedTerminal',
+        };
+        const multiStepInput = {
+            run: (_: any, state: any) => {
+                Object.assign(state.config, expectedConfig);
+                return Promise.resolve();
+            },
+        };
+        multiStepFactory
+            .setup((f) => f.create())
+            .returns(() => multiStepInput as any)
+            .verifiable(typemoq.Times.once()); // this should be called only once.
+
+        launchResolver
+            .setup((a) => a.resolveDebugConfiguration(typemoq.It.isAny(), typemoq.It.isAny(), typemoq.It.isAny()))
+            .returns(() => Promise.resolve(expectedConfig as any))
+            .verifiable(typemoq.Times.exactly(2)); // this should be called twice with the same config.
+
+        await configService.resolveDebugConfiguration(folder, {} as any);
+        await configService.resolveDebugConfiguration(folder, {} as any);
+
+        multiStepFactory.verifyAll();
+        launchResolver.verifyAll();
+    });
 });