feat(cli): add --ci option to run test command

cli/services/GitAffected.ts

@@ -1,20 +1,66 @@
-import simpleGit from 'simple-git'
+import execa from 'execa'
 
 import { Challenge } from './Challenge'
 import { Solution } from './Solution'
 
-const git = simpleGit()
-
 const solutionsRegex = new RegExp(
   /challenges\/[\s\S]*\/solutions\/(c|cpp|cs|dart|java|javascript|python|rust|typescript)\/[\s\S]*\/(solution|Solution).(c|cpp|cs|dart|java|js|py|rs|ts)/
 )
 
-class GitAffected {
+export interface GitAffectedOptions {
+  isContinuousIntegration: boolean
+}
+
+export class GitAffected implements GitAffectedOptions {
+  public isContinuousIntegration: boolean
+
+  constructor (options: GitAffectedOptions) {
+    this.isContinuousIntegration = options.isContinuousIntegration
+  }
+
+  public parseGitOutput (output: string): string[] {
+    return output
+      .split('\n')
+      .map((line) => line.trim())
+      .filter((line) => line.length > 0)
+  }
+
+  public async getFilesUsingBaseAndHead (
+    base: string,
+    head: string
+  ): Promise<string[]> {
+    const { stdout } = await execa.command(
+      `git diff --name-only --relative ${base} ${head}`
+    )
+    return this.parseGitOutput(stdout)
+  }
+
+  public async getUncommittedFiles (): Promise<string[]> {
+    return await this.getFilesUsingBaseAndHead('HEAD', '.')
+  }
+
+  public async getLatestPushedCommit (): Promise<string> {
+    const latestCommit = this.isContinuousIntegration ? '~1' : ''
+    const { stdout } = await execa.command(`git rev-parse origin/master${latestCommit}`)
+    return stdout
+  }
+
+  public async getUnpushedFiles (): Promise<string[]> {
+    return await this.getFilesUsingBaseAndHead(
+      await this.getLatestPushedCommit(),
+      '.'
+    )
+  }
+
   public async getAffectedSolutions (): Promise<Solution[]> {
-    await git.add('.')
-    const diff = await git.diff(['--name-only', '--staged'])
-    const affectedSolutionsPaths = diff.split('\n').filter((currentDiff) => {
-      return solutionsRegex.test(currentDiff)
+    const files = Array.from(
+      new Set([
+        ...(await this.getUnpushedFiles()),
+        ...(await this.getUncommittedFiles())
+      ])
+    )
+    const affectedSolutionsPaths = files.filter((filePath) => {
+      return solutionsRegex.test(filePath)
     })
     return affectedSolutionsPaths.map((solution) => {
       const [, challengeName, , programmingLanguageName, solutionName] =
@@ -29,5 +75,3 @@ class GitAffected {
     })
   }
 }
-
-export const gitAffected = new GitAffected()