feat(manager/nuget): Support single file package directives (renovatebot#40040)

* Add nuget capability to read packages from cs files

This is useful for dotnet source files that make use
of the .NET 10 feature to have single file projects,
where packages and sdks can be defined in a source
file.

* Add tests to validate that the nuget.config file is respected for single csharp files

* Apply PR linter suggestion for prettier code

* Remove unnecessary try-catch to increase code coverage

* Update phrasing in documentation

Co-authored-by: RahulGautamSingh <rahultesnik@gmail.com>

* Use codeblock instead of fixture

* Remove unused import

* Remove unnecessary fixtures and only verify required methods are called

* Fix imports in single-chsarp-file.ts

* Fix import ordering

* Increase code block indent

---------

Co-authored-by: RahulGautamSingh <rahultesnik@gmail.com>
Co-authored-by: Michael Kriese <michael.kriese@visualon.de>

Author: 3 people

lib/modules/manager/nuget/extract.spec.ts

@@ -7,6 +7,7 @@ import type { RepoGlobalConfig } from '../../../config/types.ts';
 import { DotnetVersionDatasource } from '../../datasource/dotnet-version/index.ts';
 import type { ExtractConfig } from '../types.ts';
 import { extractPackageFile } from './index.ts';
+import * as nugetExtractUtil from './util.ts';
 
 const config: ExtractConfig = {};
 
@@ -577,5 +578,59 @@ describe('modules/manager/nuget/extract', () => {
         expect(await extractPackageFile('{{', packageFile, config)).toBeNull();
       });
     });
+
+    describe('single-csharp-file', () => {
+      it('reads sdk and package directives', async () => {
+        const packageFile = 'single-csharp-file/singlefile.cs';
+        const contents = codeBlock`
+          #:sdk Some.Sdk@6.0.0
+          #:package Some.NuGet.Package@3.0.1
+
+          // https://devblogs.microsoft.com/dotnet/announcing-dotnet-run-app/
+
+          Console.WriteLine("Hello World!");
+          `;
+        expect(await extractPackageFile(contents, packageFile, config)).toEqual(
+          {
+            deps: [
+              {
+                datasource: 'nuget',
+                currentValue: '6.0.0',
+                depName: 'Some.Sdk',
+                depType: 'msbuild-sdk',
+              },
+              {
+                datasource: 'nuget',
+                currentValue: '3.0.1',
+                depName: 'Some.NuGet.Package',
+                depType: 'nuget',
+              },
+            ],
+          },
+        );
+      });
+    });
+
+    describe('single-csharp-file-nuget', () => {
+      it('calls applyRegistries to honor nuget.config files if present', async () => {
+        const packageFile = 'single-csharp-file-nuget/singlefile.cs';
+        const contents = codeBlock`
+          #:sdk Some.Sdk@6.0.0
+          #:package Some.NuGet.Package@3.0.1
+
+          // https://devblogs.microsoft.com/dotnet/announcing-dotnet-run-app/
+
+          Console.WriteLine("Hello World!");
+          `;
+
+        const applyRegistriesSpy = vi
+          .spyOn(nugetExtractUtil, 'applyRegistries')
+          .mockImplementation((deps: any) => deps);
+
+        await extractPackageFile(contents, packageFile, config);
+
+        expect(applyRegistriesSpy).toHaveBeenCalled();
+      });
+    });
   });
 });

lib/modules/manager/nuget/extract.ts

@@ -13,6 +13,7 @@ import type {
   PackageFileContent,
 } from '../types.ts';
 import { extractMsbuildGlobalManifest } from './extract/global-manifest.ts';
+import { extractPackagesFromSingleCsharpFile } from './extract/single-csharp-file.ts';
 import type { DotnetToolsManifest, NugetPackageDependency } from './types.ts';
 import {
   applyRegistries,
@@ -204,6 +205,14 @@ export async function extractPackageFile(
     return extractMsbuildGlobalManifest(content, packageFile, registries);
   }
 
+  if (packageFile.endsWith('.cs')) {
+    return extractPackagesFromSingleCsharpFile(
+      content,
+      packageFile,
+      registries,
+    );
+  }
+
   // Simple xml validation.
   // Should start with `<` and end with `>` after trimming all whitespace
   if (!regEx(/^\s*<.+>$/m).test(content.trim())) {

lib/modules/manager/nuget/extract/single-csharp-file.ts

@@ -0,0 +1,38 @@
+import { regEx } from '../../../../util/regex.ts';
+import { NugetDatasource } from '../../../datasource/nuget/index.ts';
+import type { PackageDependency, PackageFileContent } from '../../types.ts';
+import type { NugetPackageDependency, Registry } from '../types.ts';
+import { applyRegistries } from '../util.ts';
+
+// regex for finding
+// #:package Name@Version
+// or
+// #:sdk Name@Version
+const packageRegex = regEx(
+  /^#:(?<type>package|sdk)\s+(?<depName>[A-Za-z0-9_.-]+)@(?<currentValue>[0-9][^\s]*)/,
+  'gm',
+);
+
+export function extractPackagesFromSingleCsharpFile(
+  content: string,
+  packageFile: string,
+  registries: Registry[] | undefined,
+): PackageFileContent | null {
+  const deps: PackageDependency[] = [];
+
+  for (const match of content.matchAll(packageRegex)) {
+    const { type, depName, currentValue } = match.groups!;
+
+    const dep: NugetPackageDependency = {
+      depName,
+      currentValue,
+      datasource: NugetDatasource.id,
+      depType: type === 'package' ? 'nuget' : 'msbuild-sdk',
+    };
+
+    applyRegistries(dep, registries);
+    deps.push(dep);
+  }
+
+  return { deps };
+}

lib/modules/manager/nuget/readme.md

@@ -20,6 +20,9 @@ For Renovate to work with .NET Framework projects, you need to update these file
 - `.props`
 - `.targets`
 
+You can also extract from the single code file projects (since `.NET 10`).
+But, you need to add those files manually to the `managerFilePatterns` as they are not supported by default.
+
 ### Disabling updates for pinned versions
 
 In NuGet, when you use versions like `Version="1.2.3"` then it means "1.2.3 or greater, up to v2"