君はPower Assertを知っているか #potatotips

potatotips #7 2015/5/15 at DeNA

Transcript

1. ܅͸
   Power Assert
   Λ஌͍ͬͯΔ͔
   FUJI Goro (@__gfx__), a software engineer in COOKPAD
   #potatotips 2014/5/15 at DeNA
   

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2. FUJI Goro (@__gfx__)
   • software engineer @ COOKPAD Inc.
   • Android / iOS ޲͚ڞ௨ϥΠϒϥϦͷઃܭɾ։ൃ
   

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3. Assertions in Java
   // EXPR͕ࣦഊ͢Δͱ throw new AssertionError() Λ࣮ߦ͢Δ
   assert foo == 42;
   !
   // comment͸AssertionErrorͷҾ਺ͱͯ͠౉͞ΕΔ
   assert foo == 42 : “with message”;
   !
   // assertແޮ࣌͸͕ࣜධՁ͞Εͳ͍ͷͰॏΊͷલఏ৚݅νΣοΫ΋Մ
   assert checkParamsButSlow(foo);
   

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4. Assertions in Android
   • AndroidͰ͸Javaͷassertจ͕࢖͑Δ
   • `assert getActivity() != null;`
   • ͨͩ͠assert͸σϑΥϧτͰແޮ
   • `adb shell setprop debug.assert 1` Ͱ༗ޮԽ
   • …Ͱ͖Δ͜ͱ΋͋Δʢ࣮ػͩͱͰ͖ͳ͍ʁʣ
   

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5. Assertionsͷ໰୊఺
   • εΠον͕ΞϓϦ͝ͱͰ͸ͳ͘୺຤͝ͱ
   • ͦ΋ͦ΋ޮ͔ͳ͔ͬͨΓ͢Δ͠
   • ։ൃऀશһͰৗʹ༗ޮʹ͢Δͱ͍͏ͷ͸೉͍͠
   • ࣦഊ࣌ͷ৘ใʹ๡͍͠
   • ৄࡉΛ௥͏ͨΊʹϒϨʔΫϙΠϯτΛ࢓ࠐΜͰ
   σόοά͢Δඞཁ͕͋Δ
   

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6. ͭΒ͍
   

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7. ͱ͜ΖͰ
   Power Assert
   Λ஌͍ͬͯ·͔͢
   

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8. Power Assert ͷػೳ
   • assertࣦഊ࣌ʹؔ܎͢Δࣜͷ஋Λදࣔ͢Δ
   def x = new File(“foo.groovy”)
   assert x.absolutePath.contains("bar")
   // shows:
   Assertion failed:
   !
   assert x.absolutePath.contains("bar")
   | | |
   | | false
   | /path/to/foo.groovy
   foo.groovy
   at foo.run(foo.groovy:4)
   

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9. ࣮૷ͷͨΊͷπʔϧνΣΠϯ
   • ࣮ߦલʹίʔυΛॻ͖׵͑Δඞཁ͕͋Δ
   • JavaScript൛͸ιʔείʔυΛॻ͖׵͑Δ
   • Spock͸ίϯύΠϧޙͷASTΛॻ͖׵͑Δ
   • ASTʹରͯ͠ϝλϓϩάϥϛϯάͰ͖Δ؀ڥ
   ͕͋Ε͹OK
   

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10. AndroidͰ΋Power Assert͕
    ࢖͍͍ͨੈքઢʹߦ͖͍ͨ…
    

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11. – OSSքͷ֨ݴ
    “ͩͬͨΒ͓લ͕΍Ε”
    

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12. ΍Γ·ͨ͠
    

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13. Android Power Assert Plugin
    • assertจΛڧ੍తʹ༗ޮԽ
    • assertࣦഊ࣌ʹ৘ใΛ௥Ճ
    • ϦϦʔεϏϧυͰ͸Կ΋͠ͳ͍
    • ࣮ߦ଎౓ʹӨڹ͸΄ͱΜͲͳ͠
    • APKͷαΠζ΋૿͑ͳ͍
    

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14. ग़ྗྫ
    assert findViewById(R.id.never).isFocused();
    

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15. σϑΥϧτͷྫ֎
    

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16. assert findViewById(R.id.never).isFocused();
    with default mode
    java.lang.NullPointerException:
    at MainActivity.onButton2Click(MainActivity.java:28)
    (…stacktrace͕ଓ͘…)
    !
    // NOTE:
    // KitKat͔Β͸΋͏গ͠৘ใ͕૿͑ͯɺͳʹ͕nullͩͬͨͷ͔Θ͔Γ΍͘͢ͳ͍ͬͯΔ
    

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17. Power Assert༗ޮͷͱ͖
    

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18. assert findViewById(R.id.never).isFocused();
    with power assert
    java.lang.NullPointerException:
    26: void onButton2Click() {
    27> assert findViewById(R.id.never).isFocused();
    27: }
    MainActivity.findViewById()=
    at MainActivity.onButton2Click(MainActivity.java:28)
    (…stacktrace͕ଓ͘…)
    

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19. ࢖͍ํ
    // The root build.gradle
    buildscript {
    dependencies {
    classpath ‘com.github.gfx:android-power-assert-plugin:0.10.+’
    }
    }
    !
    // in build.gradle of a module
    apply plugin: ‘android-power-assert’
    

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20. ͋ͱ͸assertจΛ࢖͏͚ͩ
    

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21. Power Assert ೋͭͷଆ໘
    

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22. ΞϓϦέʔγϣϯίʔυͰ࢖͏
    • ؀ڥ͕ಛఆͷঢ়ଶͰ͋Δ͜ͱΛอূ͢Δ
    • Ҿ਺ͷνΣοΫ΍nullνΣοΫͳͲ
    • Android StudioͰNPEܯࠂΛ੩ΊΔͨΊ
    • ϦϦʔε൛Ͱassertจ͸ফ͑ΔͷͰɺ͋͘·Ͱ΋
    ʮ։ൃऀ͕ਖ਼͍͠ίʔυΛॻ͍͍ͯΔ͜ͱΛอ
    ূ͢ΔʯͨΊʹ࢖͏
    

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23. ςετͰ࢖͏
    • ൚༻ςετϚονϟʔͱͯ͠࢖͏
    • JUnitͷassertEquals()ͷҾ਺ͷॱ൪Λߟ͑ͳ͘
    ͯΑ͘ͳΔ
    • ࣜͷ్தܦաΛදࣔ͢ΔͷͰɺෳ਺ͷ
    assertXXX()Λ·ͱΊΒΕΔ
    • assert obj.foo().bar().equals(“baz”)
    

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24. How it works
    

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25. JavassistʹΑΔόΠτίʔυૢ࡞
    • $assertionsDisabledΛৗʹfalseʹ͢Δ
    • assertจʢ͕ίϯύΠϧ͞ΕͨόΠτίʔυʣ
    Λݟ͚ͭͨΒपล৘ใΛूΊͯจࣈྻΛੜ੒
    ͢ΔίʔυΛૠೖ͢Δ
    • field access / method call͸try-catchͰғΜͰ
    NPEΛΩϟονˍपล৘ใΛ෇༩ͯ͠re-throw
    

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26. ՝୊
    • ෇Ճ৘ใ͕ଟ͗͢Δ
    • ͍·͸ϩʔΧϧม਺Λ͢΂ͯdump͍ͯ͠Δ
    • SpockͷΑ͏ͳࠩ෼දࣔΛ͍ͨ͠
    • ͍·͸commonsͷToStringBuilderΛ࢖͍ͬͯΔ
    • JavassistͰେྔͷίʔυΛॻ͘ͷ͸ਏ͍ͷͰɺग़ྗ
    ϑΥʔϚολΛผʹ࣮૷͢Δඞཁ͕͋Δ
    

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27. We are hiring!
    https://info.cookpad.com/jobs/
    

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28. ͝੩ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠
    https://github.com/gfx/android-power-assert-plugin
    ਓபืूத
    

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