David N Hamilton jiffle

Tricks and tips for using Strikt assertions

Strikt is very powerful, however it is sometimes hard to find particular methods. This is a handy cheatsheet.

Basics

Top-level assertions

expect, expectThat, expectCatching and expectThrows

Git History Rewriting Tricks

Removing incorrectly committed files from the last commit

This uses a Soft Reset to revert the commit, leaving the commit modifications as local working copy changes:

git reset --soft HEAD^ or git reset --soft HEAD~1

Core Language Methods

Block method	Returns	Thread	Notes
launch	Job	From Pool parameter
async	Deferred	From Pool parameter	Use `await` to get result
withTimeout	value from Coroutine	From Pool parameter
thread	Null	New thread	Not a coroutine, but same as launch

Launch Methods

Kotlin Programming Language - Part 1

Kotlin language website is at https://kotlinlang.org.

All the codes here can be copied and run on Kotlin online editor.

Basics

You do not need ; to break statements.
Comments are similar to Java or C#, /* This is comment */ for multi line comments and // for single line comment.

Kotlin provides significantly improved support for nullable (and non-nullable) types.

These are all the language and Kotlin library features that help support working with nullable types:

Fundamentals

Non-nullable type declaration:

var a: String = "abc"

Evolving Rest Services and Backward Compatibility

My aim is to define a set of rules that can be used to decide whether an incremental data change is backwardly compatible or not, list things to beware of for a particular change, and mitigations that can be put in place.

Clearly it is assumed that the services will be using API versioning, and that a major API version number change would allow any required change to that API. The scope of this document is to explore what changes can be made within a single API version.

Main Release Management models

There are four main release management models, each of which has its own requirements and challenges in versioning the APIs.

Military Style For Effective Email Communications

The military structure their communications for maximum clarity and conciseness. These are the key points to write emails in an fffective manner:

1. Prefix Email subject with keyword

Format: STATUS - Message Title

Status keywords:

Spock Useful Patterns Cheatsheet

Adding sequences of behaviour to Mocks and Stubs

The >>> operator allows a sequence of values to be returned:

myMock.someCall() >>> ['first value', 'second value', 'third value', 'etc']

This returns each string in turn. Behaviour (such as throwing exceptions) in closures cannot be used by this operator.

The >> operator allows value or behaviour (closures) to be returned

Design Patterns implemented in Java 8

These patterns are implemented using Java 8 Lambdas (together with Project Lombok annotations).

Factory Pattern

Factory I : No Parameter Constructor

Enum class:

	import com.fasterxml.jackson.annotation.JsonValue

	enum class AccountStatus(@JsonValue val text: String) {
	PENDING("Pending"),
	ACTIVE("Active"),
	EXPIRED("Expired"),
	CANCELLED("Cancelled");

	companion object {
	private val valuesByText = values().associateBy { it.text }