MacにAppium環境構築をしようとしていて、appium-doctorを使ったら以下のような警告が出ました。

WARN AppiumDoctor  ✖ android could NOT be found at '/Users/yoshikiito/Library/Android/sdk/tools/android'!
WARN AppiumDoctor  ✖ emulator could NOT be found at '/Users/yoshikiito/Library/Android/sdk/tools/emulator'!

どうも、Android SDK Toolsというのを入れていなかったのが原因のようです。

Android SDK Tools

Android StudioのPreferenceで、Appearance & Behavior > System Settings > Android SDKと進んで、SDK Toolsタブの中にあるAndroid SDK Toolsにチェックを入れてOKを押しましょう。インストールが始まります。

yoshikiito@rrcs-172-254-99-39 ~ % appium-doctor
info AppiumDoctor Appium Doctor v.1.13.1
info AppiumDoctor ### Diagnostic for necessary dependencies starting ###
info AppiumDoctor  ✔ The Node.js binary was found at: /Users/yoshikiito/.nodebrew/current/bin/node
info AppiumDoctor  ✔ Node version is 11.4.0
info AppiumDoctor  ✔ Xcode is installed at: /Applications/Xcode.app/Contents/Developer
info AppiumDoctor  ✔ Xcode Command Line Tools are installed in: /Applications/Xcode.app/Contents/Developer
info AppiumDoctor  ✔ DevToolsSecurity is enabled.
info AppiumDoctor  ✔ The Authorization DB is set up properly.
info AppiumDoctor  ✔ Carthage was found at: /usr/local/bin/carthage. Installed version is: 0.34.0
info AppiumDoctor  ✔ HOME is set to: /Users/yoshikiito
info AppiumDoctor  ✔ ANDROID_HOME is set to: /Users/yoshikiito/Library/Android/sdk
info AppiumDoctor  ✔ JAVA_HOME is set to: /Library/Java/JavaVirtualMachines/jdk1.8.0_171.jdk/Contents/Home
info AppiumDoctor  ✔ adb exists at: /Users/yoshikiito/Library/Android/sdk/platform-tools/adb
info AppiumDoctor  ✔ android exists at: /Users/yoshikiito/Library/Android/sdk/tools/android
info AppiumDoctor  ✔ emulator exists at: /Users/yoshikiito/Library/Android/sdk/tools/emulator
info AppiumDoctor  ✔ Bin directory of $JAVA_HOME is set

以下略

解消しました。