Change detection via git + rename githubToken to token (#9)

src/git.ts

@@ -0,0 +1,26 @@
+import {exec} from '@actions/exec'
+
+export async function fetchBranch(base: string): Promise<void> {
+  const exitCode = await exec('git', ['fetch', '--depth=1', 'origin', base])
+  if (exitCode !== 0) {
+    throw new Error(`Fetching branch ${base} failed, exiting`)
+  }
+}
+
+export async function getChangedFiles(base: string): Promise<string[]> {
+  let output = ''
+  const exitCode = await exec('git', ['diff-index', '--name-only', base], {
+    listeners: {
+      stdout: (data: Buffer) => (output += data.toString())
+    }
+  })
+
+  if (exitCode !== 0) {
+    throw new Error(`Couldn't determine changed files, exiting`)
+  }
+
+  return output
+    .split('\n')
+    .map(s => s.trim())
+    .filter(s => s.length > 0)
+}