When To Mock

Transcript

1. 1.

   @stuherbert When To Mock

2. 2.

   @stuherbert Introductions When To Mock

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   @stuherbert of Unit Testing The Holy Grail When To Mock

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   @stuherbert When To Mock $ git clone git@github.com:foo/bar.git $ cd

   bar $ composer install $ phpunit
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   @stuherbert When To Mock $ git clone git@github.com:foo/bar.git $ cd

   bar $ composer install $ phpunit
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   @stuherbert When To Mock $ git clone git@github.com:foo/bar.git $ cd

   bar $ composer install $ phpunit
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   @stuherbert When To Mock $ git clone git@github.com:foo/bar.git $ cd

   bar $ composer install $ phpunit
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   @stuherbert Unit Tests Should Execute Straight Out Of The Box

   When To Mock
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   @stuherbert This Was Easy In The Pre-Web World When To

   Mock
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    @stuherbert • Our code wasn’t networked • Our code used

    embedded data storage engines • Our code wasn’t multi-user When To Mock
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    @stuherbert • Our code wasn’t networked • Our code used

    embedded data storage engines • Our code wasn’t multi-user When To Mock
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    @stuherbert • Our code wasn’t networked • Our code used

    embedded data storage engines • Our code wasn’t multi-user When To Mock
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    @stuherbert Self-Contained Our Code Was When To Mock

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    @stuherbert Pre-Web Architecture Diagram When To Mock

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    @stuherbert Pre-Web Architecture Diagram When To Mock

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    @stuherbert Pre-Web Architecture Diagram When To Mock Application Stack

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    @stuherbert Talks To Things Today’s Code When To Mock

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    @stuherbert Self Contained Today’s Code Is Anything But When To

    Mock
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    @stuherbert Our Code Has Evolved From This When To Mock

    Application Stack
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    @stuherbert Our Code Now Looks Like This When To Mock

    Database Cache 1 2 3 Internal Services External Services Controller Models Views Framework Libraries Libraries Libraries
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    @stuherbert Internally, More Complexity When To Mock Database Cache 1

    2 3 Internal Services External Services Controller Models Views Framework Libraries
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    @stuherbert Internally, More Dependencies When To Mock Database Cache 1

    2 3 Internal Services External Services Controller Models Views Framework Libraries Libraries Libraries
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    @stuherbert Storage Is Now A Service When To Mock Database

    Cache 1 2 3 Internal Services External Services Controller Models Views Framework Libraries Libraries Libraries
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    @stuherbert Functionality Is Now A Service When To Mock Database

    Cache 1 2 3 Internal Services External Services Controller Models Views Framework Libraries Libraries Libraries
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    @stuherbert Apps Are Now A Service To Users When To

    Mock Database Cache 1 2 3 Internal Services External Services Controller Models Views Framework Libraries Libraries Libraries
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    @stuherbert Unit Tests Should Execute Straight Out Of The Box

    When To Mock
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    @stuherbert Good Advice? Is This Still When To Mock

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    @stuherbert Still Good Advice? • Makes testing reproducible • Ease

    of use by new project members • Supports continuous integration When To Mock
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    @stuherbert Still Good Advice? • Makes testing reproducible • Ease

    of use by new project members • Supports continuous integration When To Mock
30. 30.

    @stuherbert Still Good Advice? • Makes testing reproducible • Ease

    of use by new project members • Supports continuous integration When To Mock
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    @stuherbert Unit Tests Should Execute Straight Out Of The Box

    When To Mock ✓
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    @stuherbert Now Requires Help Making Unit Tests Execute Out Of

    The Box When To Mock
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    @stuherbert We Want To Unit Test Like This When To

    Mock Application Stack
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    @stuherbert Are Gone But Those Days When To Mock

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    @stuherbert Our App Now Needs These When To Mock Database

    Cache Internal Services External Services
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    @stuherbert If We Mock These When To Mock Database Cache

    Internal Services External Services
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    @stuherbert We Can Unit Test Without Them When To Mock

    Database Cache Internal Services External Services
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    @stuherbert & We Can Simulate Failure Too When To Mock

    Database Cache Internal Services External Services
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    @stuherbert Three Key Questions When To Mock

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    @stuherbert • Can we mock all the things? • Should

    we mock all the things? • Should we mock inside our app? When To Mock
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    @stuherbert • Can we mock all the things? • Should

    we mock all the things? • Should we mock inside our app? When To Mock
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    @stuherbert • Can we mock all the things? • Should

    we mock all the things? • Should we mock inside our app? When To Mock
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    @stuherbert All The Things? Can We Mock When To Mock

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    @stuherbert • Given enough time and effort, yes we can

    When To Mock
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    @stuherbert All The Things? Should We Mock When To Mock

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    @stuherbert • Who is going to build the mocks? •

    How do you prove your mock behaves accurately today? • How do you prove your mock still behaves accurately tomorrow? When To Mock
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    @stuherbert • Who is going to build the mocks? •

    How do you prove your mock behaves accurately today? • How do you prove your mock still behaves accurately tomorrow? When To Mock
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    @stuherbert • Who is going to build the mocks? •

    How do you prove your mock behaves accurately today? • How do you prove your mock still behaves accurately tomorrow? When To Mock
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    @stuherbert • A mock can only be as good as

    the author’s understanding of whatever is being mocked • Tests using rotted mocks will continue to pass, but the code will fail when shipped When To Mock
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    @stuherbert • A mock can only be as good as

    the author’s understanding of whatever is being mocked • Tests using rotted mocks will continue to pass, but the code will fail when shipped When To Mock
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    @stuherbert Test what we can, mock what we have to

    When To Mock
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    @stuherbert Inside Our App? Should We Mock When To Mock

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    @stuherbert Our Code? What Happens Inside When To Mock

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    @stuherbert • computation • branching • input / output When

    To Mock
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    @stuherbert • computation • branching • input / output When

    To Mock
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    @stuherbert • computation • branching • input / output When

    To Mock
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    @stuherbert Forming Execution Paths When To Mock

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    @stuherbert One Execution Path Each Unit Test Exercises When To

    Mock
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    @stuherbert Such As This When To Mock

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    @stuherbert Or This When To Mock

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    @stuherbert Or This When To Mock

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    @stuherbert The Code You Call? What Happens When You Mock

    When To Mock
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    @stuherbert Adding Mocks Shortens The Paths We Can Test When

    To Mock
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    @stuherbert Take A Code Path When To Mock

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    @stuherbert Inject A Mock When To Mock

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    @stuherbert Shorter Code Path When To Mock

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    @stuherbert Behind The Mock? But What About The Code When

    To Mock
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    @stuherbert ? Unreachable Code When To Mock ? ? ?

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    @stuherbert Unreachable Code Mocks Inside Your App Create When To

    Mock
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    @stuherbert Is Untestable Code Unreachable Code When To Mock

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    @stuherbert What Is The Risk From The Code That You

    Can’t Test? When To Mock
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    @stuherbert Key Questions • How do you prove your mock

    behaves accurately today? • How do you prove your mock still behaves accurately tomorrow? When To Mock
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    @stuherbert • How do you prove your mock behaves accurately

    today? • How do you prove your mock still behaves accurately tomorrow? When To Mock
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    @stuherbert • A mock can only be as good as

    the author’s understanding of whatever is being mocked • Tests using rotted mocks will continue to pass, but the code will fail when shipped When To Mock
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    @stuherbert The Best Approach Mocks Are Sometimes When To Mock

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    @stuherbert Why? When To Mock

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    @stuherbert Is Reachable Not Every Code Path When To Mock

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    @stuherbert Testing For Failure • How do you get bad

    responses from the code you call? • How do you trigger your error handling? When To Mock
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    @stuherbert To Test For Failure Mocks Are A Great Way

    When To Mock
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    @stuherbert In Summary When To Mock

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    @stuherbert Test what we can, mock what we have to

    When To Mock
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    @stuherbert Unit Tests Should Execute Straight Out Of The Box

    When To Mock
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    @stuherbert Unit Tests Should Execute Straight Out Of The Box

    When To Mock ✗
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    @stuherbert Unit Tests Should Execute Straight Out Of The Box

    As Long As Test Accuracy Is Not Compromised When To Mock ✓
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    @stuherbert Unit Tests Should Be One Of Several Layers In

    Your Test Strategy When To Mock
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    @stuherbert Use Other Layers To Test For Things You Can’t

    Prove Because Of Your Mocks When To Mock
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    @stuherbert • Storyplayer for factory acceptance testing • Behat /

    BDD for product acceptance testing When To Mock
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    @stuherbert Thank You Any Questions? When To Mock