feat: spawn the user's editor to edit commit messages

lib/landing_session.js

@@ -11,7 +11,9 @@ const {
   runAsync, runSync, forceRunAsync
 } = require('./run');
 const Session = require('./session');
-const { shortSha, isGhAvailable } = require('./utils');
+const {
+  shortSha, isGhAvailable, getEditor
+} = require('./utils');
 
 const isWindows = process.platform === 'win32';
 
@@ -345,7 +347,21 @@ class LandingSession extends Session {
       return true;
     }
 
-    // TODO: fire the configured git editor on that file
+    const editor = await getEditor({ git: true });
+    if (editor) {
+      try {
+        await forceRunAsync(
+          editor,
+          [`"${messageFile}"`],
+          { ignoreFailure: false, spawnArgs: { shell: true } }
+        );
+        await runAsync('git', ['commit', '--amend', '-F', messageFile]);
+        return true;
+      } catch {
+        cli.error('Failed to edit the message using the configured editor');
+      }
+    }
+
     cli.log(`Please manually edit ${messageFile}, then run\n` +
       `\`git commit --amend -F ${messageFile}\` ` +
       'to finish amending the message');

lib/utils.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const which = require('which');
+const { forceRunAsync } = require('./run');
 
 exports.ascending = function(a, b) {
   if (a === b) return 0;
@@ -36,3 +37,32 @@ exports.isGhAvailable = function isGhAvailable() {
   }
   return isGhAvailableCache;
 };
+
+/**
+ * Returns the user's preferred text editor command.
+ * @param {object} [options]
+ * @param {boolean} [options.git] - Whether to try the GIT_EDITOR environment
+ * variable or `git config`.
+ * @returns {string|null}
+ */
+exports.getEditor = async function getEditor(options = {}) {
+  const {
+    git = false
+  } = options;
+
+  if (git) {
+    if (process.env.GIT_EDITOR) {
+      return process.env.GIT_EDITOR;
+    }
+    const out = await forceRunAsync(
+      'git',
+      ['config', 'core.editor'],
+      { captureStdout: 'lines' }
+    );
+    if (out && out[0]) {
+      return out[0];
+    }
+  }
+
+  return process.env.VISUAL || process.env.EDITOR || null;
+};