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asumikam
Harnessing the Power of
Mocks and Stubs in PHPUnit
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͓Α͏ʙ
Good Morning
Everyone!
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Welcome to Japan!
ຊΑ͏ͦ͜
ຊΑ͏ͦ͜
ຊΑ͏ͦ͜
I am Asumi 🍊
on X, phpc.sosial, and so on!
Please follow me 🫶
SNS is @asumikam
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belong to Linkage,
Community Sponsor
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am The Organizer of
PHP Conference Odawara
Next: April 10, 2027
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I usually live
as a Ninja
in Odawara
🥷🏯🍥
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Anyway
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My talk is about
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Question:
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Why do we write tests?
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Why do we write tests?
To improve quality!
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Why do we write tests?
To improve quality! To reduce bugs!
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Why do we write tests?
To improve quality! To reduce bugs!
Because my senior told me to write it…
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My answer is:
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To make my development
process easier.
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With tests, we can:
✴ Express documentation / speci
fi
cation
✴ Ease code review
✴ Catch regressions early
✴ Improve design
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But there are some problems
in writing tests 😿
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Using “real” things for
everything gets painful…
Unstable, Slow, Costly, or Out of Scope
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So, we use test doubles.
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I talk about:
First-half
The difference between mocks and stubs
(Test doubles, mocks, stubs, Anti-patterns,…)
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I talk about:
Second-half
Best test double practices in PHPUnit
(Migration problems, and the
fi
xes)
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#1
The difference
between mocks and stubs
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#1 The difference between mocks and stubs
Mocks:
Stubs:
Assertion
Imitation and
Imitation
The Difference Is
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l
Unit Testing: Principles, Practices, and Patterns
Chapter 5. Mocks and test fragility
#1 The difference between mocks and stubs
Mocks help to emulate and examine outcoming
interactions.
These interactions are calls the SUT makes to its
dependencies to change their state.
Mocks Behave As Imitations and Assertions
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l
Unit Testing: Principles, Practices, and Patterns
Chapter 5. Mocks and test fragility
#1 The difference between mocks and stubs
Stubs help to emulate incoming interactions.
These interactions are calls the SUT makes to its
dependencies to get input data.
Stubs Behave as Imitations Only
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No Test Doubles
#1 The difference between mocks and stubs
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Use Mocks — Blurred a Little
#1 The difference between mocks and stubs
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Use Stubs — Blurred Pretty Much
#1 The difference between mocks and stubs
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createMock
createStub
Let's compare!
#1 The difference between mocks and stubs
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createMock
createStub
Target for
mocking / stubbing
#1 The difference between mocks and stubs
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createMock
createStub
Imitation
#1 The difference between mocks and stubs
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createMock
createStub
Assertion
#1 The difference between mocks and stubs
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createMock
createStub
#1 The difference between mocks and stubs
It is very simple.
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#1 The difference between mocks and stubs
શʹཧղͨ͠
͔ΜͥΜ Γ͔͍
kanzen / ni / rikai / shita
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#1 The difference between mocks and stubs
શʹཧղͨ͠
͔ΜͥΜ Γ͔͍
kanzen / ni / rikai / shita
I am now an expert
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When to Use
Mocks vs. Stubs
#1 The difference between mocks and stubs
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My answer is
whether the dependency
belongs to the speci
fi
cation.
#1 The difference between mocks and stubs
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✴ Test code must express the speci
fi
cation.
✴ Reading tests should reveal the behavior without
product code.
✴ I use real objects whenever possible.
✴ Prefer Classical style rather than London style
✴ But when they're slow or complex, I reach for Test
Doubles.
My Core Philosophy
#1 The difference between mocks and stubs
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✴ If yes, use mocks.
✴ You care about the behavior / side effect.
✴ Assert it happened.
✴ If no, use stubs.
✴ You just need the return value.
✴ The interaction itself doesn't matter.
Do You Want to Assert It as Part of the Spec?
#1 The difference between mocks and stubs
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When this goes right
your test reads like a spec.
When this goes wrong
let's look at what happens.
#1 The difference between mocks and stubs
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Overuse Antipatterns
#1 The difference between mocks and stubs
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✴ Used well, test doubles bring the spec into focus.
✴ Misused, they do the opposite.
✴ Overused mocks or stubs share one outcome:
the test no longer expresses the spec.
When Overused, Tests Get Worse
#1 The difference between mocks and stubs
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Overused Mocks
#1 The difference between mocks and stubs
= Fragile Tests
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✴ Refactoring turns green to red —
the behavior is
fi
ne, but the test breaks.
✴ The test locks in calls, args, and order —
it knows the inside too well.
✴ It asserts "HOW it's done," not "WHAT it should do.”
✴ Good tests should survive any refactor,
but a fragile test can’t.
Overused Mocks = Fragile Tests
#1 The difference between mocks and stubs
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#1 The difference between mocks and stubs
Overused Stubs
= Blank-Check Tests
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✴ Tests stay green —
even when the real dependency quietly changes.
✴ The stub freezes the world at a speci
fi
c time.
When reality drifts, the stub doesn't notice.
✴ Green here means "it ran." Not "it works.”
✴ Good tests should prove the behavior is correct,
but a blank-check test can’t.
Overused Stubs = Blank-Check Tests
#1 The difference between mocks and stubs
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Mocks or Stubs?
Let the Spec Decide.
#1 The difference between mocks and stubs
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✴ Overuse turns tests into a liability —
not the asset they should be.
✴ The check: "Does this test express the spec I actually
care about?"
✴ My rule: real objects by default. Test doubles only
when they get in the way.
Let the Spec Decide
#1 The difference between mocks and stubs
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Tests Are Messages —
to Your Teammates,
to Your Future Self.
#1 The difference between mocks and stubs
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✴ When you're clear on what spec to convey,
mocks and stubs really start to work for you.
✴ The right choice shifts with your design, your layers,
your team.
✴ So make that judgment together.
Tests Are Messages — to Your Teammates,
to Your Future Self.
#1 The difference between mocks and stubs
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#2
Best Practices
in the Latest Environment
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Let's review how PHPUnit handles
mocks and stubs.
#2 Best Practices in the Latest Environment
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We Used to Build Everything with getMock()
in PHPUnit 4.x
This style was my
fi
rst experience of test doubles 😆
#2 Best Practices in the Latest Environment
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We Got createMock() at First
in PHPUnit 5.x
But we still used createMock as stubs.
#2 Best Practices in the Latest Environment
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We Got createStub() at First
in PHPUnit 8.x
We can distinguish stubs from mocks! (But same internal behavior)
#2 Best Practices in the Latest Environment
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10
11
12
13
createStub() + expects() → silently ignored
10.0.0
11.0.0 createStub() + expects() → [warning] hard deprecated
12.0.0 createStub() + expects() → [exception] removed
12.5.0 createMock() without expects() → [notice] added
12.5.5 any() → [soft deprecated]
13.0.0 any() → [hard deprecated]
13.0.2 with*() without expects() → [hard deprecated]
12.5.11 with*() on stubs → [soft deprecated]
#2 Best Practices in the Latest Environment
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10
11
12
13
createStub() + expects() → silently ignored
10.0.0
11.0.0 createStub() + expects() → [warning] hard deprecated
12.0.0 createStub() + expects() → [exception] removed
12.5.0 createMock() without expects() → [notice] added
12.5.5 any() → [soft deprecated]
13.0.0 any() → [hard deprecated]
13.0.2 with*() without expects() → [hard deprecated]
12.5.11 with*() on stubs → [soft deprecated]
#2 Best Practices in the Latest Environment
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10
11
12
13
createStub() + expects() → silently ignored
10.0.0
11.0.0 createStub() + expects() → [warning] hard deprecated
12.0.0 createStub() + expects() → [exception] removed
12.5.0 createMock() without expects() → [notice] added
12.5.5 any() → [soft deprecated]
13.0.0 any() → [hard deprecated]
13.0.2 with*() without expects() → [hard deprecated]
12.5.11 with*() on stubs → [soft deprecated]
#2 Best Practices in the Latest Environment
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10
11
12
13
createStub() + expects() → silently ignored
10.0.0
11.0.0 createStub() + expects() → [warning] hard deprecated
12.0.0 createStub() + expects() → [exception] removed
12.5.0 createMock() without expects() → [notice] added
12.5.5 any() → [soft deprecated]
13.0.0 any() → [hard deprecated]
13.0.2 with*() without expects() → [hard deprecated]
12.5.11 with*() on stubs → [soft deprecated]
#2 Best Practices in the Latest Environment
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The Basic Idea is
Mocks Can Not Be Used as Stubs
Stubs Can Not Be Used as Mocks
#2 Best Practices in the Latest Environment
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Best Practices for Handling
Mocks and Stubs in PHPUnit
Are Evolving.
#2 Best Practices in the Latest Environment
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✴ PHPUnit is getting intentional about the distinction
— not just naming it, but enforcing it at the API level
✴ That means version upgrades now come with a cost
your old doubles need to express intent
✴ Let's walk through what that looks like in practice —
through my own migration
PHPUnit Has Been Drawing a Clearer Line
#2 Best Practices in the Latest Environment
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Upgrade PHP to 8.5
and PHPUnit to 12.5.x
#2 Best Practices in the Latest Environment
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No content
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A Vast Number of N
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Upgrade PHP to 8.5 and PHPUnit to 12.5.x
Ran the tests — 615 PHPUnit Notices
l
No expectations were configured for the mock object for
XXX.Consider refactoring your test code to use a test stub
instead.
The #[AllowMockObjectsWithoutExpectations] attribute can
be used to opt out of this check.
#2 Best Practices in the Latest Environment
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Here is an example
#2 Best Practices in the Latest Environment
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I made shared mocks in setUp
#2 Best Practices in the Latest Environment
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In tests, I use this getSUT method
#2 Best Practices in the Latest Environment
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And these are example tests
#2 Best Practices in the Latest Environment
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This test has all mocks properly con
fi
gured ✅
#2 Best Practices in the Latest Environment
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This test has some mocks uncon
fi
gured 😣
#2 Best Practices in the Latest Environment
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Every Mock Now Requires an Assertion
✴ This makes sense, but it completely breaks the way
we used to write tests.
✴ A mock with no expects() = effectively a stub
✴ So it triggers the PHPUnit Notice
✴ the "." becomes an “N”
#2 Best Practices in the Latest Environment
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The "Migration Reality" Is
Happening everywhere.
#2 Best Practices in the Latest Environment
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Dealing With Mock Without Expectation Notices
✴ Situation: Shared setup() methods used for both
mocking and stubbing
✴ Solution 1: Replace; use createStub() for assertion
✴ Solution 2: Opt-out using the attribute:
#[AllowMockObjectsWithoutExpectations]
How to deal with "No expectation were con
fi
gured for the mock object"
https://github.com/sebastianbergmann/phpunit/issues/6437
Case 1
#2 Best Practices in the Latest Environment
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How to Ignore All Mock Without Expectation
Notices at Once
✴ Situation: You want a global con
fi
guration to ignore all
notices.
✴ Solution: There is no way to do that in PHPUnit. Deal
with each notice one by one.
Provider a new con
fi
guration option to ignore mock without expectations
https://github.com/sebastianbergmann/phpunit/issues/6439
Case 2
#2 Best Practices in the Latest Environment
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Dealing With Mock Without Expectation Notices
in Symfony
✴ Situation: The Symfony framework ended up with many
notices in PHPUnit 12.5
✴ Solution: Replace createMock() with createStub() in each
module
[Validator] ConstraintValidatorTestCase has PHPUnit notices with PHPUnit 12.5
https://github.com/symfony/symfony/issues/62669
Case 3
#2 Best Practices in the Latest Environment
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Dealing With Mock Without Expectation Notices
in Drupal
✴ Situation: The Drupal CMS ended up with many notices
in PHPUnit 12.5
✴ Solution: Broken down to 37 subtasks,
replace createMock() with createStub() in each module
[meta] Refactor tests to use stubs instead of mocks where mocks do not con
fi
gure expectations
https://www.drupal.org/project/drupal/issues/3561671
Case 4
#2 Best Practices in the Latest Environment
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Dealing With Mock Without Expectation Notices
in CakePHP
✴ Situation: The CakePHP framework ended up with many
notices in PHPUnit 12.5
✴ Solution: Fixed each test similarly to other cases at
fi
rst.
✴ Then, deciding that the PHPUnit API is not as stable,
and ended up using Mockery.
https://github.com/cakephp/cakephp/pull/19196
https://github.com/cakephp/cakephp/pull/19259
Case 5
#2 Best Practices in the Latest Environment
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How About Laravel?
✴ Laravel's mocking helpers are built on Mockery, not
PHPUnit’s native mocks.
✴ Since Mockery 1.0:
✴ $double->allows() = stub behavior
✴ $double->expects() = mock behavior
✴ PHPUnit is now enforcing what Mockery has exposed via
API since 2017
#2 Best Practices in the Latest Environment
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What I Did: Back to Basics
✴ PHPUnit is highly motivated to draw a clear line
between mocks and stubs.
✴ I asked myself — what makes a good test?
✴ A good test expresses the speci
fi
cation
✴ To do that, test doubles must express intent too
✴ So I committed to
fi
xing every Notice, step by step
#2 Best Practices in the Latest Environment
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My Migration Steps
(1)Bulk-add the opt-out attribute via a custom rector
→ PHP 8.5 done
(2)Replace what rectorphp/rector-phpunit can replace
(3)Peel that attribute off one-by-one
(4)And then, on to PHPUnit 12.5.x 👏
#2 Best Practices in the Latest Environment
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rectorphp/rector-phpunit
Auto-converts createMock → createStub
✴ It reduces the count and is worth trying.
✴ Sent a PR for intersection-type support — merged 😘
#2 Best Practices in the Latest Environment
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And now,
We Are on PHPUnit 13.x.x
#2 Best Practices in the Latest Environment
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The any() Matcher
Is Hard Deprecated from 13.0.0
Migration Point 1
Scheduled to be removed in 14.0.0
#2 Best Practices in the Latest Environment
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The any() Matcher Is Hard Deprecated
#2 Best Practices in the Latest Environment
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The any() Matcher Is Hard Deprecated
#2 Best Practices in the Latest Environment
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The any() Matcher Is Hard Deprecated
#2 Best Practices in the Latest Environment
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The any() Matcher Is Hard Deprecated
#2 Best Practices in the Latest Environment
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The any() Matcher Is Hard Deprecated
#2 Best Practices in the Latest Environment
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with*() Without expects()
Is Hard Deprecated from 13.0.2
Migration Point 2
Scheduled to be removed in 14.0.0
#2 Best Practices in the Latest Environment
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with*() Without expects() Is Hard Deprecated
#2 Best Practices in the Latest Environment
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#2 Best Practices in the Latest Environment
with*() Without expects() Is Hard Deprecated
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#2 Best Practices in the Latest Environment
with*() Without expects() Is Hard Deprecated
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#2 Best Practices in the Latest Environment
with*() Without expects() Is Hard Deprecated
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atLeast() With a Non-Positive Argument
Is Hard Deprecated from 13.0.2
Migration Point 3
Scheduled to be removed in 14.0.0
#2 Best Practices in the Latest Environment
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atLeast() With a Non-Positive Argument Is Hard Deprecated
#2 Best Practices in the Latest Environment
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atLeast() With a Non-Positive Argument Is Hard Deprecated
#2 Best Practices in the Latest Environment
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atLeast() With a Non-Positive Argument Is Hard Deprecated
#2 Best Practices in the Latest Environment
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atLeast() With a Non-Positive Argument Is Hard Deprecated
#2 Best Practices in the Latest Environment
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atLeast() With a Non-Positive Argument Is Hard Deprecated
#2 Best Practices in the Latest Environment
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✴ My migration points are:
✴ the any() matcher is deprecated
✴ with*() without expects() is deprecated
✴ atLeast() with a non-positive argument is deprecated
✴ It closes off "ambiguous mocks" at the spec level
✴ “assert with createMock, imitate with createStub"
— now enforced by the API
And Now, We Are on PHPUnit 13.x.x
#2 Best Practices in the Latest Environment
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Takeaways
#2 Best Practices in the Latest Environment
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When You Assert and Imitate: Use createMock()
✴ createMock() only when it is part of the spec
✴ Always pair with expects($this->once()) or exactly(n)
✴ Always pair with() with expects()
✴ Drop any()
✴ Drop atLeast() with non positive-arguments
#2 Best Practices in the Latest Environment
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When You Imitate Only: Use createStub
✴ createStub() for dependencies you don't need to assert
✴ Con
fi
gure with method() + willReturn(), nothing else
✴ Never write expects()
✴ Never use with()
#2 Best Practices in the Latest Environment
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Spec-Expressing Tests Become the
"Guardrail" of the Al
✴ The clearer the line, the more valuable "spec-expressing
tests" become
✴ If the spec lives in the test, Al has something to lean on for
the next move
✴ Even when the spec changes, "what to protect" stays in
the test
✴ An ambiguous test makes no guardrail
#2 Best Practices in the Latest Environment
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#3
Summary
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I write test code
to make my development
process easier.
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If I need test double with
imitation and assertion,
I use mocks.
If only imitation, I use stubs.
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PHPUnit is evolving
to distinguish stubs from mocks,
Let's make a clear distinction
between them.
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You Know What to Say…😋
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શʹཧղͨ͠
͔ΜͥΜ Γ͔͍
kanzen / ni / rikai / shita
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And,
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I love PHPUnit!
Thank you
Sebastian Bergmann🫶
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He gave the keynote speech
in PHP Conference Odawara
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Brought PHPUnit
collaboration
merch
for my hosted
conference.
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🍊͋Γ͕ͱ͏🍊
Thanks!
Enjoy your 2 days!!