blocks|key|4412177|text|编写自定义匹配器可以清理您的测试逻辑：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4412178|public+class+AMatcher+extends+TypeSafeMatcher<A>+{
+++A+actual;
+++public+AMatcher(A+actual)+{+this.actual+=+actual;+}

+++protected+boolean+matchesSafely(A+a)+{
++++++return+a.equals(actual);++//+or+compare+individual+fields...
+++}+

+++public+void+describeTo(Description+d)+{
++++++d.appendText("should+match+"%2Bactual);+//+printed+out+when+a+match+isn't+found.
+++}
}|code-block|syntax|javascript|4412179|然后，使用它：|4412180|assertThat(list,+allOf(new+AMatcher(a1),+new+AMatcher(a2)));|4412181|或者，如果你不想创建A的实例来创建匹配器，可以创建一个接受'name‘和'val’参数的AMatcher构造函数。|4412182|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Writing a custom matcher cleans up your test logic:

<pre><code>public class AMatcher extends TypeSafeMatcher&lt;A&gt; {
 A actual;
 public AMatcher(A actual) { this.actual = actual; }

 protected boolean matchesSafely(A a) {
 return a.equals(actual); // or compare individual fields...
 } 

 public void describeTo(Description d) {
 d.appendText("should match "+actual); // printed out when a match isn't found.
 }
}
</code></pre>

then, to use it:

<pre><code>assertThat(list, allOf(new AMatcher(a1), new AMatcher(a2)));
</code></pre>

or, if you don't want to create instances of A to create a matcher, create an AMatcher constructor that takes your 'name' and 'val' arguments.

blocks|key|4412129|text|您可以根据自己的需要实现自定义的Matcher，例如检查一些具有名称的项是否具有相同的值字段：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4412130|final+class+FooTest+{

++++static+final+class+Foo+{

++++++++final+int+val;
++++++++final+String+name;

++++++++//+all+args+constructor
++++}

++++//+custom+matcher
++++static+final+class+FoosHasSameValues+extends+TypeSafeMatcher<List<Foo>>+{

++++++++private+final+Set<String>+names;

++++++++//+all+args+constructor

++++++++FoosHasSameValues(final+String...+names)+{
++++++++++++this(new+HashSet<>(Arrays.asList(names)));
++++++++}

++++++++@Override
++++++++protected+boolean+matchesSafely(final+List<Foo>+items)+{
++++++++++++final+List<Integer>+values+=+items.stream()
++++++++++++++++//+filter+only+items+with+specified+names
++++++++++++++++.filter(i+->+this.names.contains(i.name))
++++++++++++++++//+select+only+values
++++++++++++++++.map(i+->+i.val)
++++++++++++++++.collect(Collectors.toList());
++++++++++++if+(values.size()+!=+this.names.size())+{
++++++++++++++++//+matching+failed+if+list+doesn't+contains+all
++++++++++++++++//+needed+items+with+names
++++++++++++++++return+false;
++++++++++++}
++++++++++++//+check+https://stackoverflow.com/a/29288616/1723695
++++++++++++return+values.stream().distinct().limit(2).count()+<=+1;
++++++++}

++++++++@Override
++++++++public+void+describeTo(final+Description+description)+{
++++++++++++description.appendText("has+items+[")
++++++++++++++++.appendValue(String.join(",+",+this.names))
++++++++++++++++.appendText("]+with+same+values");
++++++++}
++++}

++++@Test
++++void+testMatchers()+throws+Exception+{
++++++++MatcherAssert.assertThat(
++++++++++++Arrays.asList(
++++++++++++++++new+Foo("first",+1),
++++++++++++++++new+Foo("second",+1),
++++++++++++++++new+Foo("third",+2)
++++++++++++),
++++++++++++new+FoosHasSameValues("first",+"second")
++++++++);
++++}
}|code-block|syntax|javascript|4412131|entityMap^0|G|7|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

You can implement custom <code>Matcher</code> for your needs, e.g. to check that some items with names has same values fields:

<pre><code>final class FooTest {

 static final class Foo {

 final int val;
 final String name;

 // all args constructor
 }

 // custom matcher
 static final class FoosHasSameValues extends TypeSafeMatcher&lt;List&lt;Foo&gt;&gt; {

 private final Set&lt;String&gt; names;

 // all args constructor

 FoosHasSameValues(final String... names) {
 this(new HashSet&lt;&gt;(Arrays.asList(names)));
 }

 @Override
 protected boolean matchesSafely(final List&lt;Foo&gt; items) {
 final List&lt;Integer&gt; values = items.stream()
 // filter only items with specified names
 .filter(i -&gt; this.names.contains(i.name))
 // select only values
 .map(i -&gt; i.val)
 .collect(Collectors.toList());
 if (values.size() != this.names.size()) {
 // matching failed if list doesn't contains all
 // needed items with names
 return false;
 }
 // check https://stackoverflow.com/a/29288616/1723695
 return values.stream().distinct().limit(2).count() &lt;= 1;
 }

 @Override
 public void describeTo(final Description description) {
 description.appendText("has items [")
 .appendValue(String.join(", ", this.names))
 .appendText("] with same values");
 }
 }

 @Test
 void testMatchers() throws Exception {
 MatcherAssert.assertThat(
 Arrays.asList(
 new Foo("first", 1),
 new Foo("second", 1),
 new Foo("third", 2)
 ),
 new FoosHasSameValues("first", "second")
 );
 }
}
</code></pre>

Let's say I have a <code>List&lt;A&gt;</code> where 

<pre><code>class A {
 private Integer val;
 private String name;
}
</code></pre>

and in my test case I get this list, with uncertain size, and content. What I wish to do is to compare <code>val</code> field of two list elements that I know has to be in the list with given <code>name</code> fields;

<pre><code>List&lt;A&gt; list = logic.getList();
assertThat(list, allOf(hasItems(hasProperty("name", equalTo("first")), 
 hasItems(hasProperty("val", equalTo(***value from another member with name = "second"))));
</code></pre>

How can I achieve this, or is this even possible with Hamcrest Matchers?

How to compare members of a list of complex objects with Hamcrest?

假设我有一个List<A>，其中class A { private Integer val; private String name;}在我的测试用例中，我得到了这个列表，大小和内容都不确定。我想做的是将我知道必须在列表中的两个列表元素的val字段与给定的name字段进行比较；List<A> list = ...

问如何将复杂对象列表的成员与Hamcrest进行比较？
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