more unit tests and corresponding refactoring (#174)

src/git-directory-helper.ts

@@ -0,0 +1,91 @@
+import * as core from '@actions/core'
+import * as fs from 'fs'
+import * as fsHelper from './fs-helper'
+import * as io from '@actions/io'
+import * as path from 'path'
+import {IGitCommandManager} from './git-command-manager'
+
+export async function prepareExistingDirectory(
+  git: IGitCommandManager | undefined,
+  repositoryPath: string,
+  repositoryUrl: string,
+  clean: boolean
+): Promise<void> {
+  let remove = false
+
+  // Check whether using git or REST API
+  if (!git) {
+    remove = true
+  }
+  // Fetch URL does not match
+  else if (
+    !fsHelper.directoryExistsSync(path.join(repositoryPath, '.git')) ||
+    repositoryUrl !== (await git.tryGetFetchUrl())
+  ) {
+    remove = true
+  } else {
+    // Delete any index.lock and shallow.lock left by a previously canceled run or crashed git process
+    const lockPaths = [
+      path.join(repositoryPath, '.git', 'index.lock'),
+      path.join(repositoryPath, '.git', 'shallow.lock')
+    ]
+    for (const lockPath of lockPaths) {
+      try {
+        await io.rmRF(lockPath)
+      } catch (error) {
+        core.debug(`Unable to delete '${lockPath}'. ${error.message}`)
+      }
+    }
+
+    try {
+      // Checkout detached HEAD
+      if (!(await git.isDetached())) {
+        await git.checkoutDetach()
+      }
+
+      // Remove all refs/heads/*
+      let branches = await git.branchList(false)
+      for (const branch of branches) {
+        await git.branchDelete(false, branch)
+      }
+
+      // Remove all refs/remotes/origin/* to avoid conflicts
+      branches = await git.branchList(true)
+      for (const branch of branches) {
+        await git.branchDelete(true, branch)
+      }
+
+      // Clean
+      if (clean) {
+        if (!(await git.tryClean())) {
+          core.debug(
+            `The clean command failed. This might be caused by: 1) path too long, 2) permission issue, or 3) file in use. For futher investigation, manually run 'git clean -ffdx' on the directory '${repositoryPath}'.`
+          )
+          remove = true
+        } else if (!(await git.tryReset())) {
+          remove = true
+        }
+
+        if (remove) {
+          core.warning(
+            `Unable to clean or reset the repository. The repository will be recreated instead.`
+          )
+        }
+      }
+    } catch (error) {
+      core.warning(
+        `Unable to prepare the existing repository. The repository will be recreated instead.`
+      )
+      remove = true
+    }
+  }
+
+  if (remove) {
+    // Delete the contents of the directory. Don't delete the directory itself
+    // since it might be the current working directory.
+    core.info(`Deleting the contents of '${repositoryPath}'`)
+    for (const file of await fs.promises.readdir(repositoryPath)) {
+      await io.rmRF(path.join(repositoryPath, file))
+    }
+  }
+}