Address comments

Author: savannahostrowski

src/extension/debugger/configuration/providers/fastapiLaunch.ts

@@ -35,6 +35,7 @@ export async function buildFastAPILaunchDebugConfiguration(
     const autoArgs = state.folder ? tryResolveFastApiArgs(state.folder, fastApiPaths) : undefined;
 
     let args: string[];
+    let manuallyEnteredAValue = false;
     if (autoArgs) {
         args = autoArgs;
     } else {
@@ -46,6 +47,7 @@ export async function buildFastAPILaunchDebugConfiguration(
             return;
         }
         args = ['run', entered];
+        manuallyEnteredAValue = true;
     }
 
     const config: Partial<LaunchRequestArguments> = {
@@ -58,6 +60,8 @@ export async function buildFastAPILaunchDebugConfiguration(
     };
     sendTelemetryEvent(EventName.DEBUGGER_CONFIGURATION_PROMPTS, undefined, {
         configurationType: DebugConfigurationType.launchFastAPI,
+        autoDetectedFastAPIMainPyPath: !!autoArgs,
+        manuallyEnteredAValue,
     });
     Object.assign(state.config, config);
 }

src/extension/debugger/configuration/utils/configuration.ts

@@ -82,7 +82,7 @@ export async function getFastApiPaths(folder: WorkspaceFolder | undefined) {
     return fastApiPaths;
 }
 
-export function tryResolveFastApiArgs(folder: WorkspaceFolder, paths: Uri[]): string[] | undefined {
+export function tryResolveFastApiArgs(folder: WorkspaceFolder, paths: readonly Uri[]): string[] | undefined {
     if (paths.length !== 1) {
         return undefined;
     }

src/test/unittest/configuration/dynamicdebugConfigurationService.unit.test.ts

@@ -0,0 +1,65 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+'use strict';
+
+import { expect } from 'chai';
+import * as path from 'path';
+import * as sinon from 'sinon';
+import { Uri, WorkspaceFolder } from 'vscode';
+import { DynamicPythonDebugConfigurationService } from '../../../extension/debugger/configuration/dynamicdebugConfigurationService';
+import * as configurationUtils from '../../../extension/debugger/configuration/utils/configuration';
+
+suite('Debugging - Dynamic Debug Configuration Service', () => {
+    const folder: WorkspaceFolder = { uri: Uri.file('/work'), name: 'ws', index: 0 };
+    let service: DynamicPythonDebugConfigurationService;
+    let getFastApiPathsStub: sinon.SinonStub;
+
+    setup(() => {
+        service = new DynamicPythonDebugConfigurationService();
+        sinon.stub(configurationUtils, 'getDjangoPaths').resolves([]);
+        sinon.stub(configurationUtils, 'getFlaskPaths').resolves([]);
+        getFastApiPathsStub = sinon.stub(configurationUtils, 'getFastApiPaths');
+    });
+
+    teardown(() => {
+        sinon.restore();
+    });
+
+    const fastApiProviders = async () => {
+        const result = await service.provideDebugConfigurations(folder);
+        return (result ?? []).filter((c) => c.name?.includes('FastAPI'));
+    };
+
+    test('No FastAPI detected → no FastAPI configs offered', async () => {
+        getFastApiPathsStub.resolves([]);
+
+        const fastApi = await fastApiProviders();
+        expect(fastApi).to.have.length(0);
+    });
+
+    test('Single match at workspace root → project config uses resolved path, file variant uses ${file}', async () => {
+        getFastApiPathsStub.resolves([Uri.file('/work/main.py')]);
+
+        const fastApi = await fastApiProviders();
+        expect(fastApi).to.have.length(2);
+        expect(fastApi[0]).to.include({ name: 'Python Debugger: FastAPI', module: 'fastapi' });
+        expect(fastApi[0].args).to.deep.equal(['run', 'main.py']);
+        expect(fastApi[1]).to.include({ name: 'Python Debugger: FastAPI File', module: 'fastapi' });
+        expect(fastApi[1].args).to.deep.equal(['run', '${file}']);
+    });
+
+    test('Single match in subdirectory → project config passes path explicitly', async () => {
+        getFastApiPathsStub.resolves([Uri.file('/work/backend/app/main.py')]);
+
+        const fastApi = await fastApiProviders();
+        expect(fastApi[0].args).to.deep.equal(['run', path.join('backend', 'app', 'main.py')]);
+    });
+
+    test('Multiple matches → project config falls back to plain `fastapi run`', async () => {
+        getFastApiPathsStub.resolves([Uri.file('/work/svc-a/main.py'), Uri.file('/work/svc-b/main.py')]);
+
+        const fastApi = await fastApiProviders();
+        expect(fastApi[0].args).to.deep.equal(['run']);
+    });
+});

src/test/unittest/configuration/providers/fastapiLaunch.unit.test.ts

@@ -138,3 +138,36 @@ suite('Debugging - Configuration Provider FastAPI', () => {
         expect(state.config).to.be.deep.equal(config);
     });
 });
+
+suite('Debugging - tryResolveFastApiArgs', () => {
+    const workspaceFolder = (root: string) => ({
+        uri: Uri.file(root),
+        name: 'ws',
+        index: 0,
+    });
+
+    test('Returns undefined for empty paths', () => {
+        expect(configurationUtils.tryResolveFastApiArgs(workspaceFolder('/work'), [])).to.equal(undefined);
+    });
+
+    test('Returns undefined for multiple paths', () => {
+        const paths = [Uri.file('/work/svc-a/main.py'), Uri.file('/work/svc-b/main.py')];
+        expect(configurationUtils.tryResolveFastApiArgs(workspaceFolder('/work'), paths)).to.equal(undefined);
+    });
+
+    test('Returns resolved path for single root-level match', () => {
+        const paths = [Uri.file('/work/main.py')];
+        expect(configurationUtils.tryResolveFastApiArgs(workspaceFolder('/work'), paths)).to.deep.equal([
+            'run',
+            'main.py',
+        ]);
+    });
+
+    test('Returns resolved path for single nested match', () => {
+        const paths = [Uri.file('/work/backend/app/main.py')];
+        expect(configurationUtils.tryResolveFastApiArgs(workspaceFolder('/work'), paths)).to.deep.equal([
+            'run',
+            path.join('backend', 'app', 'main.py'),
+        ]);
+    });
+});