Java 8 brings power to testing!

Java 8 brings power to testing!
Marcin Zajączkowski @SolidSoftBlog http://blog.solidsoft.info/
Poznań, 30th January 2015

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3 interesting companies

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Java 8
The most revolutionary Java version released in recent
years

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Java 8
years
Focus on lambda expressions and method references

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Java 8
years
Constructions known from Groovy or Scala become
available (even if they look uglier)

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Java 8
years
Constructions known from Groovy or Scala become
available (even if they look uglier)
How can it improve our testing code and testing tools?

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Case study 1:
AssertJ

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AssertJ - Fluent assertions for Java
Continuation of FEST-Assert
Large set of strongly typed assertions
a
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) /
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.
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1
)
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(
d
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2
, d
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3
)
;
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(
l
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) /
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, S
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y a
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5
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) /
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S
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e
(
7
)
.
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K
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y
(
4
2
)
.
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n
t
r
y
(
1
3
, "
F
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y
"
)
.
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u
e
(
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d
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y
"
)
;
Additional modules for Guava, Joda-Time, Neo4j and
Android

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AssertJ - Java 8 edition
A completely separate branch
New method signatures
New classes
Support for new features
j
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v
a
.
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l
.
O
p
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Date and Time API (JSR 310)

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Manual fields extraction (antipattern)
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s F
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w {
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;
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}
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> {
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;
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}
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<
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> n
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s = n
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w A
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<
>
(
)
;
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r (
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w f
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w : f
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) {
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d
(
f
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.
g
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t
N
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(
)
)
;
}
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h
a
t
(
n
a
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e
s
)
.
c
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t
a
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n
s
(
"
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d
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f
"
, "
L
e
g
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a
s
"
)
.
d
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N
o
t
C
o
n
t
a
i
n
(
"
S
a
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n
"
)
;
}

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AssertJ - fields extraction
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s
s F
e
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w {
p
r
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t
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g n
a
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;
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e
;
(
.
.
.
)
}
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s F
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s I
t
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<
F
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w
> {
p
r
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v
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i
n
a
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<
F
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w
> f
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s
;
(
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.
)
}
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) {
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)
; /
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O
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}
Field name as String - error-prone and hard to refactor
No strong typing

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AssertJ - fields extraction - Java 8
@
T
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e
(
) {
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p
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r
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g
(
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w
:
:
g
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N
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e
)
.
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s
(
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f
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a
s
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) /
/
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t
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g
.
d
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s
N
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C
o
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t
a
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n
(
"
S
a
u
r
o
n
"
)
; /
/
S
t
r
i
n
g
}
Method reference - safer, easy to refactor
Strong typing
Preview in assertj-core-java8 1.0.0m1
Will be available in AssertJ 2.0

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Manual fields extraction - Java 8
(antipattern)
Why not pure Java 8 Streams?

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Manual fields extraction - Java 8
(antipattern)
Why not pure Java 8 Streams?
@
T
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p
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8
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) { /
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'
t d
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<
S
t
r
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g
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s = S
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a
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p
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.
s
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(
f
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s
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r
a
t
o
r
(
)
,
.
m
a
p
(
F
e
l
l
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w
:
:
g
e
t
N
a
m
e
)
.
c
o
l
l
e
c
t
(
C
o
l
l
e
c
t
o
r
s
.
t
o
L
i
s
t
(
)
)
;
a
s
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e
r
t
T
h
a
t
(
n
a
m
e
s
)
.
c
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n
t
a
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s
(
"
G
a
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f
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.
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t
a
i
n
(
"
S
a
u
r
o
n
"
)
;
}
Functional, but still bloated

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Case study 2:
Awaitility

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Awaitility
Smart asynchronous call testing
Adaptable waiting for completion
Finishes as quickly as condition is fulfilled
No more s
l
e
e
p
(
5
0
0
0
) in tests
Separate support for Groovy and Scala traits and closures

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Awaitility
Communication with queue
p
u
b
l
i
c i
n
t
e
r
f
a
c
e M
e
s
s
a
g
e
Q
u
e
u
e
F
a
c
a
d
e {
v
o
i
d s
e
n
d
P
i
n
g
(
)
;
i
n
t g
e
t
N
u
m
b
e
r
O
f
R
e
c
e
i
v
e
d
P
a
c
k
e
t
s
(
)
;
}
@
T
e
s
t
p
u
b
l
i
c v
o
i
d r
e
s
p
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n
s
e
S
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d
B
e
A
v
a
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l
a
b
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A
f
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r
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o
m
e
T
i
m
e
P
r
o
x
y
E
d
i
t
i
o
n
(
) {
/
/
w
h
e
n
q
u
e
u
e
F
a
c
a
d
e
.
s
e
n
d
P
i
n
g
(
)
;
/
/
t
h
e
n
a
w
a
i
t
(
)
.
u
n
t
i
l
C
a
l
l
(
t
o
(
q
u
e
u
e
F
a
c
a
d
e
)
.
g
e
t
N
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m
b
e
r
O
f
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c
e
i
v
e
d
P
a
c
k
e
t
s
(
)
, e
q
u
a
l
T
o
(
1
)
)
}

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Awaitility
Assertions & matchers
Clear and verbose error message:
C
o
n
d
i
t
i
o
n
T
i
m
e
o
u
t
E
x
c
e
p
t
i
o
n
: M
e
s
s
a
g
e
Q
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e
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e
F
a
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e
.
g
e
t
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b
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d
P
a
c
k
e
t
s
(
)
e
x
p
e
c
t
e
d <
1
> b
u
t w
a
s <
0
> w
i
t
h
i
n 5 s
e
c
o
n
d
s
.

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Awaitility
Assertions & matchers
Clear and verbose error message:
C
o
n
d
i
t
i
o
n
T
i
m
e
o
u
t
E
x
c
e
p
t
i
o
n
: M
e
s
s
a
g
e
Q
u
e
u
e
F
a
c
a
d
e
.
g
e
t
N
u
m
b
e
r
O
f
R
e
c
e
i
v
e
d
P
a
c
k
e
t
s
(
)
e
x
p
e
c
t
e
d <
1
> b
u
t w
a
s <
0
> w
i
t
h
i
n 5 s
e
c
o
n
d
s
.
Drawbacks
Not so easy with complicated matching expression
I personally prefer AssertJ over Hamcrest

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Awaitility with Java 8
Java 7:
@
T
e
s
t
p
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c v
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d r
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p
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a
b
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e
A
f
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r
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e
T
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e
(
) {
/
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w
h
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q
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e
u
e
F
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c
a
d
e
.
s
e
n
d
P
i
n
g
(
)
;
/
/
t
h
e
n
a
w
a
i
t
(
)
.
u
n
t
i
l
(
g
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b
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r
O
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c
e
i
v
e
d
P
a
c
k
e
t
s
(
)
, e
q
u
a
l
T
o
(
1
)
)
;
}
p
r
i
v
a
t
e C
a
l
l
a
b
l
e
 g
e
t
N
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m
b
e
r
O
f
R
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c
e
i
v
e
d
P
a
c
k
e
t
s
(
) {
r
e
t
u
r
n n
e
w C
a
l
l
a
b
l
e

(
) {
p
u
b
l
i
c I
n
t
e
g
e
r c
a
l
l
(
) t
h
r
o
w
s E
x
c
e
p
t
i
o
n {
r
e
t
u
r
n q
u
e
u
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e
.
g
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N
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m
b
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c
e
i
v
e
d
P
a
c
k
e
t
s
(
)
;
}
}
;
}

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Awaitility with Java 8
Java 8 - lambda expression
@
T
e
s
t
p
u
b
l
i
c v
o
i
d r
e
s
p
o
n
s
e
S
h
o
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l
d
B
e
A
v
a
i
l
a
b
l
e
A
f
t
e
r
S
o
m
e
T
i
m
e
8
(
) {
/
/
w
h
e
n
q
u
e
u
e
F
a
c
a
d
e
.
s
e
n
d
P
i
n
g
(
)
;
/
/
t
h
e
n
a
w
a
i
t
(
)
.
u
n
t
i
l
(
(
) -
> q
u
e
u
e
F
a
c
a
d
e
.
g
e
t
N
u
m
b
e
r
O
f
R
e
c
e
i
v
e
d
P
a
c
k
e
t
s
(
)
, e
q
u
a
l
T
o
(
1
)
)
;
}
Java 8 - method reference
a
w
a
i
t
(
)
.
u
n
t
i
l
(
q
u
e
u
e
F
a
c
a
d
e
:
:
g
e
t
N
u
m
b
e
r
O
f
R
e
c
e
i
v
e
d
P
a
c
k
e
t
s
, e
q
u
a
l
T
o
(
1
)
)
;
Question - do I need Hamcrest in Java 8 world?

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Awaitility with Java 8 without Hamcrest
@
T
e
s
t
p
u
b
l
i
c v
o
i
d r
e
s
p
o
n
s
e
S
h
o
u
l
d
B
e
A
v
a
i
l
a
b
l
e
A
f
t
e
r
S
o
m
e
T
i
m
e
J
a
v
a
8
E
d
i
t
i
o
n
(
) {
/
/
w
h
e
n
q
u
e
u
e
F
a
c
a
d
e
.
s
e
n
d
P
i
n
g
(
)
;
/
/
t
h
e
n
a
w
a
i
t
(
)
.
u
n
t
i
l
(
(
) -
> q
u
e
u
e
F
a
c
a
d
e
.
g
e
t
N
u
m
b
e
r
O
f
R
e
c
e
i
v
e
d
P
a
c
k
e
t
s
(
) =
= 1
)
;
}
Clear and verbose error message?
C
o
n
d
i
t
i
o
n
T
i
m
e
o
u
t
E
x
c
e
p
t
i
o
n
: D
e
l
a
y
e
d
D
e
l
i
v
e
r
y
M
Q
F
a
c
a
d
e
.
g
e
t
N
u
m
b
e
r
O
f
R
e
c
e
i
v
e
d
P
a
c
k
e
t
s
(
)
e
x
p
e
c
t
e
d <
1
> b
u
t w
a
s <
0
> w
i
t
h
i
n 5 s
e
c
o
n
d
s
.

View Slide

Awaitility with Java 8 without Hamcrest
@
T
e
s
t
p
u
b
l
i
c v
o
i
d r
e
s
p
o
n
s
e
S
h
o
u
l
d
B
e
A
v
a
i
l
a
b
l
e
A
f
t
e
r
S
o
m
e
T
i
m
e
J
a
v
a
8
E
d
i
t
i
o
n
(
) {
/
/
w
h
e
n
q
u
e
u
e
F
a
c
a
d
e
.
s
e
n
d
P
i
n
g
(
)
;
/
/
t
h
e
n
a
w
a
i
t
(
)
.
u
n
t
i
l
(
(
) -
> q
u
e
u
e
F
a
c
a
d
e
.
g
e
t
N
u
m
b
e
r
O
f
R
e
c
e
i
v
e
d
P
a
c
k
e
t
s
(
) =
= 1
)
;
}
Clear and verbose error message?
C
o
n
d
i
t
i
o
n
T
i
m
e
o
u
t
E
x
c
e
p
t
i
o
n
: D
e
l
a
y
e
d
D
e
l
i
v
e
r
y
M
Q
F
a
c
a
d
e
.
g
e
t
N
u
m
b
e
r
O
f
R
e
c
e
i
v
e
d
P
a
c
k
e
t
s
(
)
e
x
p
e
c
t
e
d <
1
> b
u
t w
a
s <
0
> w
i
t
h
i
n 5 s
e
c
o
n
d
s
.
Not anymore
C
o
n
d
i
t
i
o
n
T
i
m
e
o
u
t
E
x
c
e
p
t
i
o
n
: C
o
n
d
i
t
i
o
n w
i
t
h l
a
m
b
d
a e
x
p
r
e
s
s
i
o
n i
n
A
w
a
i
t
i
l
i
t
y
A
s
y
n
c
h
T
e
s
t w
a
s n
o
t f
u
l
f
i
l
l
e
d w
i
t
h
i
n 5 s
e
c
o
n
d
s
.
Expected 1, but was 0? 2? 3? -1?

View Slide

Awaitility and AssertJ
@
T
e
s
t
p
u
b
l
i
c v
o
i
d r
e
s
p
o
n
s
e
S
h
o
u
l
d
B
e
A
v
a
i
l
a
b
l
e
A
f
t
e
r
S
o
m
e
T
i
m
e
J
a
v
a
8
E
d
i
t
i
o
n
2
(
) {
/
/
w
h
e
n
q
u
e
u
e
F
a
c
a
d
e
.
s
e
n
d
P
i
n
g
(
)
;
/
/
t
h
e
n
a
w
a
i
t
(
)
.
u
n
t
i
l
(
(
) -
>
a
s
s
e
r
t
T
h
a
t
(
q
u
e
u
e
F
a
c
a
d
e
.
g
e
t
N
u
m
b
e
r
O
f
R
e
c
e
i
v
e
d
P
a
c
k
e
t
s
(
)
)
.
i
s
E
q
u
a
l
T
o
(
1
)
)
;
}
Still clear and verbose error message from AssertJ:
C
o
n
d
i
t
i
o
n
T
i
m
e
o
u
t
E
x
c
e
p
t
i
o
n
: C
o
n
d
i
t
i
o
n d
e
f
i
n
e
d a
s a l
a
m
b
d
a e
x
p
r
e
s
s
i
o
n
i
n A
w
a
i
t
i
l
i
t
y
A
s
y
n
c
h
T
e
s
t e
x
p
e
c
t
e
d
:
<
[
1
]
> b
u
t w
a
s
:
<
[
0
]
> w
i
t
h
i
n 5 s
e
c
o
n
d
s
.
Would it possible?

View Slide

Awaitility and AssertJ - Internals
One evening of hacking
p
u
b
l
i
c A
s
s
e
r
t
i
o
n
C
o
n
d
i
t
i
o
n
(
f
i
n
a
l R
u
n
n
a
b
l
e s
u
p
p
l
i
e
r
, C
o
n
d
i
t
i
o
n
S
e
t
t
i
n
g
s s
e
t
t
i
n
g
s
)
i
f (
s
u
p
p
l
i
e
r =
= n
u
l
l
) { t
h
r
o
w n
e
w I
l
l
e
g
a
l
A
r
g
u
m
e
n
t
E
x
c
e
p
t
i
o
n
(
"
.
.
.
"
)
; }
C
a
l
l
a
b
l
e
 c
a
l
l
a
b
l
e = n
e
w C
a
l
l
a
b
l
e

(
) {
p
u
b
l
i
c B
o
o
l
e
a
n c
a
l
l
(
) t
h
r
o
w
s E
x
c
e
p
t
i
o
n {
t
r
y {
s
u
p
p
l
i
e
r
.
r
u
n
(
)
;
r
e
t
u
r
n t
r
u
e
;
} c
a
t
c
h (
A
s
s
e
r
t
i
o
n
E
r
r
o
r e
) {
l
a
s
t
E
x
c
e
p
t
i
o
n
M
e
s
s
a
g
e = e
.
g
e
t
M
e
s
s
a
g
e
(
)
;
r
e
t
u
r
n f
a
l
s
e
;
}
}
}
;
c
o
n
d
i
t
i
o
n
A
w
a
i
t
e
r = n
e
w C
o
n
d
i
t
i
o
n
A
w
a
i
t
e
r
(
c
a
l
l
a
b
l
e
, s
e
t
t
i
n
g
s
) {
@
O
v
e
r
r
i
d
e
p
r
o
t
e
c
t
e
d S
t
r
i
n
g g
e
t
T
i
m
e
o
u
t
M
e
s
s
a
g
e
(
) {
r
e
t
u
r
n s
u
p
p
l
i
e
r
.
g
e
t
C
l
a
s
s
(
)
.
g
e
t
N
a
m
e
(
) + " " + l
a
s
t
E
x
c
e
p
t
i
o
n
M
e
s
s
a
g
e
;
}
}
;
}

View Slide

Awaitility and AssertJ - Internals
One evening of hacking
p
u
b
l
i
c A
s
s
e
r
t
i
o
n
C
o
n
d
i
t
i
o
n
(
f
i
n
a
l R
u
n
n
a
b
l
e s
u
p
p
l
i
e
r
, C
o
n
d
i
t
i
o
n
S
e
t
t
i
n
g
s s
e
t
t
i
n
g
s
)
i
f (
s
u
p
p
l
i
e
r =
= n
u
l
l
) { t
h
r
o
w n
e
w I
l
l
e
g
a
l
A
r
g
u
m
e
n
t
E
x
c
e
p
t
i
o
n
(
"
.
.
.
"
)
; }
C
a
l
l
a
b
l
e
 c
a
l
l
a
b
l
e = n
e
w C
a
l
l
a
b
l
e

(
) {
p
u
b
l
i
c B
o
o
l
e
a
n c
a
l
l
(
) t
h
r
o
w
s E
x
c
e
p
t
i
o
n {
t
r
y {
s
u
p
p
l
i
e
r
.
r
u
n
(
)
;
r
e
t
u
r
n t
r
u
e
;
} c
a
t
c
h (
A
s
s
e
r
t
i
o
n
E
r
r
o
r e
) {
l
a
s
t
E
x
c
e
p
t
i
o
n
M
e
s
s
a
g
e = e
.
g
e
t
M
e
s
s
a
g
e
(
)
;
r
e
t
u
r
n f
a
l
s
e
;
}
}
}
;
c
o
n
d
i
t
i
o
n
A
w
a
i
t
e
r = n
e
w C
o
n
d
i
t
i
o
n
A
w
a
i
t
e
r
(
c
a
l
l
a
b
l
e
, s
e
t
t
i
n
g
s
) {
@
O
v
e
r
r
i
d
e
p
r
o
t
e
c
t
e
d S
t
r
i
n
g g
e
t
T
i
m
e
o
u
t
M
e
s
s
a
g
e
(
) {
r
e
t
u
r
n s
u
p
p
l
i
e
r
.
g
e
t
C
l
a
s
s
(
)
.
g
e
t
N
a
m
e
(
) + " " + l
a
s
t
E
x
c
e
p
t
i
o
n
M
e
s
s
a
g
e
;
}
}
;
}
1.6.0+

View Slide

Case study 3:
Mockito

View Slide

Mockito - argument capturing
Capture reference to object passed as argument in
method call
Alternative for matchers
Useful for complex object verification
A
r
g
u
m
e
n
t
C
a
p
t
o
r
<
S
h
i
p
S
e
a
r
c
h
C
r
i
t
e
r
i
a
> c
a
p
t
o
r =
A
r
g
u
m
e
n
t
C
a
p
t
o
r
.
f
o
r
C
l
a
s
s
(
S
h
i
p
S
e
a
r
c
h
C
r
i
t
e
r
i
a
.
c
l
a
s
s
)
;
v
e
r
i
f
y
(
t
s
)
.
f
i
n
d
N
u
m
b
e
r
O
f
S
h
i
p
s
I
n
R
a
n
g
e
B
y
C
r
i
t
e
r
i
a
(
c
a
p
t
o
r
.
c
a
p
t
u
r
e
(
)
)
;
a
s
s
e
r
t
T
h
a
t
(
c
a
p
t
o
r
.
g
e
t
V
a
l
u
e
(
)
.
g
e
t
M
i
n
i
m
u
m
R
a
n
g
e
(
)
)
.
i
s
L
e
s
s
T
h
a
n
(
2
0
0
0
)
;
Bloated - 3 lines to assert one value

View Slide

Mockito - argument capturing - Java 8
Why not embed AssertJ inside a capturing call?
v
e
r
i
f
y
(
t
s
)
.
f
i
n
d
N
u
m
b
e
r
O
f
S
h
i
p
s
I
n
R
a
n
g
e
B
y
C
r
i
t
e
r
i
a
(
a
s
s
e
r
t
A
r
g
(
s
c -
> a
s
s
e
r
t
T
h
a
t
(
s
c
.
g
e
t
M
i
n
i
m
u
m
R
a
n
g
e
(
)
)
.
i
s
L
e
s
s
T
h
a
n
(
2
0
0
0
)
)
)
;
Clear and verbose error message from AssertJ
A
r
g
u
m
e
n
t a
s
s
e
r
t
i
o
n e
r
r
o
r
:
t
s
.
f
i
n
d
N
u
m
b
e
r
O
f
S
h
i
p
s
I
n
R
a
n
g
e
B
y
C
r
i
t
e
r
i
a
(
<
a
s
s
e
r
t
i
o
n m
a
t
c
h
e
r
>
E
x
p
e
c
t
i
n
g
:
<
3
0
0
0
>
t
o b
e l
e
s
s t
h
a
n
:
<
2
0
0
0
>
)
;
I
n
t
e
r
a
c
t
i
o
n
s w
i
t
h t
h
i
s m
o
c
k
:
t
s
.
f
i
n
d
N
u
m
b
e
r
O
f
S
h
i
p
s
I
n
R
a
n
g
e
B
y
C
r
i
t
e
r
i
a
(
S
h
i
p
S
e
a
r
c
h
C
r
i
t
e
r
i
a
{
m
i
n
i
m
u
m
R
a
n
g
e
=
3
0
0
0
, n
u
m
b
e
r
O
f
P
h
a
s
e
r
s
=
4
}
)
;

View Slide

Mockito - argument capturing - internals
p
u
b
l
i
c c
l
a
s
s A
s
s
e
r
t
i
o
n
M
a
t
c
h
e
r
<
T
> e
x
t
e
n
d
s A
r
g
u
m
e
n
t
M
a
t
c
h
e
r
<
T
> {
(
.
.
.
)
p
u
b
l
i
c A
s
s
e
r
t
i
o
n
M
a
t
c
h
e
r
(
C
o
n
s
u
m
e
r
<
T
> c
o
n
s
u
m
e
r
) {
t
h
i
s
.
c
o
n
s
u
m
e
r = c
o
n
s
u
m
e
r
;
}
@
O
v
e
r
r
i
d
e
p
u
b
l
i
c b
o
o
l
e
a
n m
a
t
c
h
e
s
(
O
b
j
e
c
t a
r
g
u
m
e
n
t
) {
t
r
y {
c
o
n
s
u
m
e
r
.
a
c
c
e
p
t
(
(
T
) a
r
g
u
m
e
n
t
)
;
r
e
t
u
r
n t
r
u
e
;
} c
a
t
c
h (
A
s
s
e
r
t
i
o
n
E
r
r
o
r e
) {
e
r
r
o
r
M
e
s
s
a
g
e = e
.
g
e
t
M
e
s
s
a
g
e
(
)
;
r
e
t
u
r
n f
a
l
s
e
;
}
}
@
O
v
e
r
r
i
d
e
p
u
b
l
i
c v
o
i
d d
e
s
c
r
i
b
e
T
o
(
D
e
s
c
r
i
p
t
i
o
n d
e
s
c
r
i
p
t
i
o
n
) { .
.
. }
p
u
b
l
i
c s
t
a
t
i
c <
T
> T a
s
s
e
r
t
A
r
g
(
C
o
n
s
u
m
e
r
<
T
> c
o
n
s
u
m
e
r
) {
M
o
c
k
i
t
o
.
a
r
g
T
h
a
t
(
n
e
w A
s
s
e
r
t
i
o
n
M
a
t
c
h
e
r
<
T
>
(
c
o
n
s
u
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(
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;
}

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Case study 4:
catch-exception

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Testing thrown exceptions - Java 7
@Test(expected = ...)
try..catch
ExpectedException
catch-exception
fluent-exception-rule

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catch-exception - Java 7
catch and verify exceptions in a single line of code
/
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h
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e
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;
can use existing AssertJ assertions for exception instances
no support for static methods and constructor calls
complicated implementation
proxy to remember and re-execute method call

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What can be simplified with Java 8?

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Everything...

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Everything...
From the project webpage:
Java 8's lambda expressions will make catch-exception
redundant.
The project have been deprecated by the original author

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The entire library (20+ classes) can be replaced with
T
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T
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(
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h
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s
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e
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s
a
g
e
(
"
T
e
s
t e
x
c
e
p
t
i
o
n
"
)
;

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catch-exception
Lambda approach already implemented in AssertJ
Will be available in AssertJ 2.0
@
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(
) {
a
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(
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)
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.
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h
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(
"
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e
p
t
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o
n
"
)
;
}
Java 7 people can use maintenance fork by Mariusz
Smykuła from Codearte

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Summary

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Summary
More compact and smarter (testing) code with Java 8

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Summary
Some things work out of the box

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Summary
Lambdas alone do not replace everything

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Summary
Some tools have to be modified to benefit

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Summary
Some tools were made obsolete completely...

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Summary
Sometimes it is required to change a mindset to see an
oportunity

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Summary
Sometimes it is required to change a mindset to see an
oportunity
There is still a lot work to do in that field
maybe it is worth to learn Java 8 features hacking some
open source tool?

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Questions/comments?
During the next break or via Twitter
Marcin Zajączkowski
http://blog.solidsoft.info/
@SolidSoftBlog
[email protected]

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Java 8 brings power to testing!

Java 8 brings power to testing!

Marcin Zajączkowski

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