feature: fallback to pre-release when no stable version is found

This allows to specify version like `3.11` or `pypy3.10` in workflows before those versions are released.
This lessen the burden for users of `setup-python` by not having to modify their workflow twice: once when a pre-release is available (e.g. `3.11-dev`) and once when the first stable release is published (e.g. `3.11`)

Author: mayeut

__tests__/data/pypy.json

@@ -1,4 +1,88 @@
 [
+  {
+    "pypy_version": "7.3.8rc2",
+    "python_version": "3.8.12",
+    "stable": false,
+    "latest_pypy": false,
+    "date": "2022-02-11",
+    "files": [
+      {
+        "filename": "pypy3.8-v7.3.8rc2-linux32.tar.bz2",
+        "arch": "i686",
+        "platform": "linux",
+        "download_url": "https://test.download.python.org/pypy/pypy3.8-v7.3.8rc2-linux32.tar.bz2"
+      },
+      {
+        "filename": "pypy3.8-v7.3.8rc2-linux64.tar.bz2",
+        "arch": "x64",
+        "platform": "linux",
+        "download_url": "https://test.download.python.org/pypy/pypy3.8-v7.3.8rc2-linux64.tar.bz2"
+      },
+      {
+        "filename": "pypy3.8-v7.3.8rc2-darwin64.tar.bz2",
+        "arch": "x64",
+        "platform": "darwin",
+        "download_url": "https://test.download.python.org/pypy/pypy3.8-v7.3.8rc2-darwin64.tar.bz2"
+      },
+      {
+        "filename": "pypy3.8-v7.3.8rc2-s390x.tar.bz2",
+        "arch": "s390x",
+        "platform": "linux",
+        "download_url": "https://test.download.python.org/pypy/pypy3.8-v7.3.8rc2-s390x.tar.bz2"
+      },
+      {
+        "filename": "pypy3.8-v7.3.8rc2-win64.zip",
+        "arch": "x64",
+        "platform": "win64",
+        "download_url": "https://test.download.python.org/pypy/pypy3.8-v7.3.8rc2-win64.zip"
+      }
+    ]
+  },
+  {
+    "pypy_version": "7.4.0rc1",
+    "python_version": "3.6.12",
+    "stable": false,
+    "latest_pypy": false,
+    "date": "2021-11-11",
+    "files": [
+      {
+        "filename": "pypy3.6-v7.4.0rc1-aarch64.tar.bz2",
+        "arch": "aarch64",
+        "platform": "linux",
+        "download_url": "https://test.download.python.org/pypy/pypy3.6-v7.4.0rc1-aarch64.tar.bz2"
+      },
+      {
+        "filename": "pypy3.6-v7.4.0rc1-linux32.tar.bz2",
+        "arch": "i686",
+        "platform": "linux",
+        "download_url": "https://test.download.python.org/pypy/pypy3.6-v7.4.0rc1-linux32.tar.bz2"
+      },
+      {
+        "filename": "pypy3.6-v7.4.0rc1-linux64.tar.bz2",
+        "arch": "x64",
+        "platform": "linux",
+        "download_url": "https://test.download.python.org/pypy/pypy3.6-v7.4.0rc1-linux64.tar.bz2"
+      },
+      {
+        "filename": "pypy3.6-v7.4.0rc1-darwin64.tar.bz2",
+        "arch": "x64",
+        "platform": "darwin",
+        "download_url": "https://test.download.python.org/pypy/pypy3.6-v7.4.0rc1-darwin64.tar.bz2"
+      },
+      {
+        "filename": "pypy3.6-v7.4.0rc1-win32.zip",
+        "arch": "x86",
+        "platform": "win32",
+        "download_url": "https://test.download.python.org/pypy/pypy3.6-v7.4.0rc1-win32.zip"
+      },
+      {
+        "filename": "pypy3.6-v7.4.0rc1-s390x.tar.bz2",
+        "arch": "s390x",
+        "platform": "linux",
+        "download_url": "https://test.download.python.org/pypy/pypy3.6-v7.4.0rc1-s390x.tar.bz2"
+      }
+    ]
+  },
   {
     "pypy_version": "7.3.3",
     "python_version": "3.6.12",
@@ -530,4 +614,4 @@
       }
     ]
   }
-]
+]

__tests__/data/versions-manifest.json

@@ -1,4 +1,29 @@
 [
+    {
+      "version": "1.2.4-beta.2",
+      "stable": false,
+      "release_url": "https://github.com/actions/sometool/releases/tag/1.2.4-beta.2-20200402.5",
+      "files": [
+        {
+          "filename": "sometool-1.2.4-linux-x64.tar.gz",
+          "arch": "x64",
+          "platform": "linux",
+          "download_url": "https://github.com/actions/sometool/releases/tag/1.2.4-beta.2-20200402.5/sometool-1.2.4-linux-x64.tar.gz"
+        },
+        {
+          "filename": "sometool-1.2.4-darwin-x64.tar.gz",
+          "arch": "x64",
+          "platform": "darwin",
+          "download_url": "https://github.com/actions/sometool/releases/tag/1.2.4-beta.2-20200402.5/sometool-1.2.4-darwin-x64.tar.gz"
+        },
+        {
+          "filename": "sometool-1.2.4-win32-x64.tar.gz",
+          "arch": "x64",
+          "platform": "win32",
+          "download_url": "https://github.com/actions/sometool/releases/tag/1.2.4-beta.2-20200402.5/sometool-1.2.4-win32-x64.tar.gz"
+        }
+      ]
+    },
     {
       "version": "1.2.3",
       "stable": true,
@@ -25,28 +50,28 @@
       ]
     },
     {
-      "version": "1.2.3-beta.2",
+      "version": "1.1.0-beta.2",
       "stable": false,
-      "release_url": "https://github.com/actions/sometool/releases/tag/1.2.3-beta.2-20200402.5",
+      "release_url": "https://github.com/actions/sometool/releases/tag/1.1.0-beta.2-20200402.5",
       "files": [
         {
-          "filename": "sometool-1.2.3-linux-x64.tar.gz",
+          "filename": "sometool-1.1.0-linux-x64.tar.gz",
           "arch": "x64",
           "platform": "linux",
-          "download_url": "https://github.com/actions/sometool/releases/tag/1.2.3-beta.2-20200402.5/sometool-1.2.3-linux-x64.tar.gz"
+          "download_url": "https://github.com/actions/sometool/releases/tag/1.1.0-beta.2-20200402.5/sometool-1.1.0-linux-x64.tar.gz"
         },
         {
-          "filename": "sometool-1.2.3-darwin-x64.tar.gz",
+          "filename": "sometool-1.1.0-darwin-x64.tar.gz",
           "arch": "x64",
           "platform": "darwin",
-          "download_url": "https://github.com/actions/sometool/releases/tag/1.2.3-20200402.5/sometool-1.2.3-darwin-x64.tar.gz"
+          "download_url": "https://github.com/actions/sometool/releases/tag/1.1.0-beta.2-20200402.5/sometool-1.1.0-darwin-x64.tar.gz"
         },
         {
-          "filename": "sometool-1.2.3-win32-x64.tar.gz",
+          "filename": "sometool-1.1.0-win32-x64.tar.gz",
           "arch": "x64",
           "platform": "win32",
-          "download_url": "https://github.com/actions/sometool/releases/tag/1.2.3-20200402.5/sometool-1.2.3-win32-x64.tar.gz"
+          "download_url": "https://github.com/actions/sometool/releases/tag/1.1.0-beta.2-20200402.5/sometool-1.1.0-win32-x64.tar.gz"
         }
       ]
     }
-]
+]

__tests__/find-pypy.test.ts

@@ -294,4 +294,19 @@ describe('findPyPyVersion', () => {
       `PyPy version 3.7 (v7.5.x) with arch ${architecture} not found`
     );
   });
+
+  it('found and install successfully, pre-release fallback', async () => {
+    spyCacheDir = jest.spyOn(tc, 'cacheDir');
+    spyCacheDir.mockImplementation(() =>
+      path.join(toolDir, 'PyPy', '3.8.12', architecture)
+    );
+    spyChmodSync = jest.spyOn(fs, 'chmodSync');
+    spyChmodSync.mockImplementation(() => undefined);
+    await expect(
+      finder.findPyPyVersion('pypy3.8', architecture, true)
+    ).resolves.toEqual({
+      resolvedPythonVersion: '3.8.12',
+      resolvedPyPyVersion: '7.3.8rc2'
+    });
+  });
 });

__tests__/finder.test.ts

@@ -83,7 +83,12 @@ describe('Finder tests', () => {
       fs.writeFileSync(`${pythonDir}.complete`, 'hello');
     });
     // This will throw if it doesn't find it in the cache and in the manifest (because no such version exists)
-    await finder.useCpythonVersion('1.2.3', 'x64', true);
+    await expect(
+      finder.useCpythonVersion('1.2.3', 'x64', true)
+    ).resolves.toEqual({
+      impl: 'CPython',
+      version: '1.2.3'
+    });
     expect(spyCoreAddPath).toHaveBeenCalled();
     expect(spyCoreExportVariable).toHaveBeenCalledWith(
       'pythonLocation',
@@ -107,14 +112,19 @@ describe('Finder tests', () => {
       const pythonDir: string = path.join(
         toolDir,
         'Python',
-        '1.2.3-beta.2',
+        '1.2.4-beta.2',
         'x64'
       );
       await io.mkdirP(pythonDir);
       fs.writeFileSync(`${pythonDir}.complete`, 'hello');
     });
     // This will throw if it doesn't find it in the manifest (because no such version exists)
-    await finder.useCpythonVersion('1.2.3-beta.2', 'x64', true);
+    await expect(
+      finder.useCpythonVersion('1.2.4-beta.2', 'x64', true)
+    ).resolves.toEqual({
+      impl: 'CPython',
+      version: '1.2.4-beta.2'
+    });
     expect(spyCoreAddPath).toHaveBeenCalled();
     expect(spyCoreExportVariable).toHaveBeenCalledWith(
       'pythonLocation',
@@ -126,6 +136,55 @@ describe('Finder tests', () => {
     );
   });
 
+  it('Finds stable Python version if it is not installed, but exists in the manifest, skipping newer pre-release', async () => {
+    const findSpy: jest.SpyInstance = jest.spyOn(tc, 'getManifestFromRepo');
+    findSpy.mockImplementation(() => <tc.IToolRelease[]>manifestData);
+
+    const installSpy: jest.SpyInstance = jest.spyOn(
+      installer,
+      'installCpythonFromRelease'
+    );
+    installSpy.mockImplementation(async () => {
+      const pythonDir: string = path.join(toolDir, 'Python', '1.2.3', 'x64');
+      await io.mkdirP(pythonDir);
+      fs.writeFileSync(`${pythonDir}.complete`, 'hello');
+    });
+    // This will throw if it doesn't find it in the cache and in the manifest (because no such version exists)
+    await expect(finder.useCpythonVersion('1.2', 'x64', true)).resolves.toEqual(
+      {
+        impl: 'CPython',
+        version: '1.2.3'
+      }
+    );
+  });
+
+  it('Finds Python version if it is not installed, but exists in the manifest, pre-release fallback', async () => {
+    const findSpy: jest.SpyInstance = jest.spyOn(tc, 'getManifestFromRepo');
+    findSpy.mockImplementation(() => <tc.IToolRelease[]>manifestData);
+
+    const installSpy: jest.SpyInstance = jest.spyOn(
+      installer,
+      'installCpythonFromRelease'
+    );
+    installSpy.mockImplementation(async () => {
+      const pythonDir: string = path.join(
+        toolDir,
+        'Python',
+        '1.1.0-beta.2',
+        'x64'
+      );
+      await io.mkdirP(pythonDir);
+      fs.writeFileSync(`${pythonDir}.complete`, 'hello');
+    });
+    // This will throw if it doesn't find it in the cache and in the manifest (because no such version exists)
+    await expect(finder.useCpythonVersion('1.1', 'x64', true)).resolves.toEqual(
+      {
+        impl: 'CPython',
+        version: '1.1.0-beta.2'
+      }
+    );
+  });
+
   it('Errors if Python is not installed', async () => {
     // This will throw if it doesn't find it in the cache and in the manifest (because no such version exists)
     let thrown = false;