Danny Preussler (Viacom), Mobile Kotlin all your tests, CodeFest 2017

https://2017.codefest.ru/lecture/1155

Kotlin was the rising star of programming languages in 2016. It not only became final with version 1.0 but also got rapidly adopted in the android community. But many companies are struggling to add Kotlin to an existing Java project. It's not easy to add a new language to an existing team. But it's much easier to introduce Kotlin to your project using the backdoor: your unit tests. So let's look at Kotlin more from a testing perspective. How does it look like to write tests in Kotlin, what possibilities of the language will help us?

Transcript

1. Kotlin all your tests Danny Preussler Android Lead, (Google Developer Expert)
2. Kotlin all your tests Danny Preussler Android Lead, (Google Developer Expert)
3. fun test() Kotlin all your tests Danny Preussler Android Lead, (Google Developer Expert)
4. @PreusslerBerlin Our world so far …
5. @PreusslerBerlin
6. @PreusslerBerlin Watch the cool kids…
7. @PreusslerBerlin But then …
8. @PreusslerBerlin
9. @PreusslerBerlin
10. @PreusslerBerlin Kotlin stole the best from the best
11. @PreusslerBerlin Kotlin stole got inspired by the best from of the best
12. @PreusslerBerlin JVM based
13. @PreusslerBerlin Functional inspired
14. @PreusslerBerlin Statically typed
15. @PreusslerBerlin Statically typed val number = 5
16. @PreusslerBerlin Designed with Android in mind
17. @PreusslerBerlin Null safe
18. @PreusslerBerlin Null safe
19. @PreusslerBerlin Reduce boilerplate
20. @PreusslerBerlin No need for Java8
21. @PreusslerBerlin Awesome tooling support
22. @PreusslerBerlin Awesome tooling support
23. @PreusslerBerlin
24. @PreusslerBerlin BUT
25. @PreusslerBerlin
26. @PreusslerBerlin “No Kotlin in production”
27. @PreusslerBerlin
28. @PreusslerBerlin But wait …
29. @PreusslerBerlin But wait … A backdoor
30. @PreusslerBerlin No one cares about your tests anyway right?
31. @PreusslerBerlin Tests are a safe place for experiments
32. @PreusslerBerlin Let’s test in Kotlin
33. @PreusslerBerlin Kotlin is expressive
34. @PreusslerBerlin @Test void testHandlesNullArguments()
35. @PreusslerBerlin @Test fun testHandlesNullArguments()
36. @PreusslerBerlin @Test fun testHandlesNullArguments()
37. @PreusslerBerlin @Test fun handlesNullArguments()
38. @PreusslerBerlin @Test fun handles_null_arguments()
39. @PreusslerBerlin @Test fun ‘handles null arguments’()
40. @PreusslerBerlin Readability first
41. @PreusslerBerlin String jsonText = "{\r\n \"deal\" : {\r\n \"isTipped\" : true,\r\n \"id\" : \"D-Company-241907\",\r\n \"areas\" : [],\r\n \"smallImageUrl\" : \"http://uat-static.groupon.de/00/00/small0000.jpg\",\r\n \"finePrint\" : \"MULTI DEAL ext Codes\",\r\n \"says\" : {\r\n \"emailContent\" : \"\",\r\n \"id\" : \"\",\r\n \"websiteContent\" : \"\",\r\n \"title\" : \"\",\r\n \"websiteContentHtml\" : \"\",\r\n \"emailContentHtml\" : \"\"\r\n },\r\n \"endAt\" : \"2014-03-31T22:59:00Z\",\r\n \"shortAnnouncementTitle\" : \"D-Company: 50% sparen in QA_AutoTestCity2\",\r\n \"placeholderUrl\" : \"http://assets2.grouponcdn.com/images/groupon/grayPlaceholder.png\",\r\n \"shippingAddressRequired\" : false,\r\n \"type\" : \"groupon\",\r\n \"isSoldOut\" : false,\r\n \"priority\" : 0,\r\n \"options\" : [\r\n {\r\n \"status\" : \"open\",\r\n \"title\" : \"MULTI DEAL ext Codes Option1\",\r\n \"isLimitedQuantity\" : false,\r\n \"tax\" : {\r\n \"amount\" : 16,\r\n \"currencyCode\" : \"EUR\",\r\n \"formattedAmount\" : \"0,16 \u20AC\"\r\n },\r\n \"minimumPurchaseQuantity\" : 1,\r\n \"expiresInDays\" : 62,\r\n \"discount\" : {\r\n \"amount\" : 100,\r\n \"currencyCode\" : \"EUR\",\r\n
42. @PreusslerBerlin val jsonText = """ { "channels":{ "BOOKING":1443439538, "GTG":1443439537, } } """
43. @PreusslerBerlin ... tested.updateNetworkStatus(networkInfo) assertFalse(tested.isCellularConnected()) assertFalse(tested.isWifiConnected()) ...
44. @PreusslerBerlin ... tested.updateNetworkStatus(networkInfo) assertFalse(tested.isNotOnAnyNetwork()) ...
45. @PreusslerBerlin fun ConnectivityReceive.isNotOnAnyNetwork(): Boolean{ return !isCellularConnecrted() && !isWifiConnected()) }
46. @PreusslerBerlin fun ConnectivityReceiver.isNotOnAnyNetwork() = { !isCellularConnecrted() && !isWifiConnected()) }
47. @PreusslerBerlin ... tested.updateNetworkStatus(networkInfo) tested.assertNotOnAnyNetwork() ...
48. @PreusslerBerlin fun ConnectivityReceiver.assertNotOnAnyNetwork(){ assertFalse(isConnected()) assertFalse(isWifiConnected()) }
49. @PreusslerBerlin Keep it short
50. @PreusslerBerlin ... Map<TYPE, Integer> signalStrength = new HashMap<>(); signalStrength.put(EDGE, 80); signalStrength.put(WIFI to 90); ...
51. @PreusslerBerlin ... val signalStrength = hashMapOf(EDGE to 80, WIFI to 90) ...
52. @PreusslerBerlin Make it consistent
53. @PreusslerBerlin assertFailsWith<NoSuchElementException>( none.get() )
54. @PreusslerBerlin What about mocks?
55. @PreusslerBerlin Kotlin Mockito github.com/nhaarman/mockito-kotlin
56. @PreusslerBerlin Syntactical Sugar around Mockito
57. @PreusslerBerlin var resources = mock<Resources>()
58. @PreusslerBerlin var resources : Resources = mock()
59. @PreusslerBerlin whenever(resources.getString(R.string.title) .thenReturn(”Title")
60. @PreusslerBerlin var resources = mock<Resources> { on { getString(R.string.title) } doReturn ”Title” }
61. @PreusslerBerlin any() * without Java8
62. @PreusslerBerlin verify(tracker).report(any()) * without Java8
63. @PreusslerBerlin tracker.report(mock()) * without Java8
64. @PreusslerBerlin verify(fragment).setArguments(bundle)
65. @PreusslerBerlin verify(fragment).setArguments(bundle)
66. @PreusslerBerlin verify(fragment).arguments = bundle
67. @PreusslerBerlin inOrder(parcel).apply { verify(parcel).writeByte(0) verify(parcel).writeString("path") }
68. @PreusslerBerlin argumentCaptor<VideoStartedReport>().apply { verify(tracker).report(capture()) assertEquals(value.id, TEST_ID) assertEquals(value.duration, TEST_DURATION) }
69. @PreusslerBerlin Kluent github.com/MarkusAmshove/Kluent
70. @PreusslerBerlin Readability first
71. @PreusslerBerlin assertEquals("hello", greeting);
72. @PreusslerBerlin greeting shouldEqual "hello"
73. @PreusslerBerlin list shouldContain “jon”
74. @PreusslerBerlin No magic here
75. @PreusslerBerlin list.shouldContain(“jon”)
76. @PreusslerBerlin infix fun <T> Array<T>.shouldContain(theThing: T)
77. @PreusslerBerlin Spek github.com/JetBrains/spek
78. @PreusslerBerlin SimpleSpec: Spek({ describe("a calculator") { val calculator = SampleCalculator() on("addition") { val sum = calculator.sum(2, 4) it("should return the sum") { assertEquals(6, sum) } } } }
79. @PreusslerBerlin Tests are a great way to learn Kotlin
80. @PreusslerBerlin Make a plan how to continue
81. @PreusslerBerlin Make a plan how to continue •tutorials
82. @PreusslerBerlin Make a plan how to continue •tutorials •hackathons
83. @PreusslerBerlin Make a plan how to continue •tutorials •hackathons •coding Kata
84. @PreusslerBerlin Build an experiment, learn from it, see prove it’s working
85. @PreusslerBerlin
86. fun test() Kotlin all your tests Danny Preussler @PreusslerBerlin