org.skyscreamer.jsonassert

Class ArrayValueMatcher<T>

java.lang.Object

org.skyscreamer.jsonassert.ArrayValueMatcher<T>

All Implemented Interfaces:

LocationAwareValueMatcher<T>, ValueMatcher<T>

public class ArrayValueMatcher<T>
extends Object
implements LocationAwareValueMatcher<T>

A value matcher for arrays. This operates like STRICT_ORDER array match, however if expected array has less elements than actual array the matching process loops through the expected array to get expected elements for the additional actual elements. In general the expected array will contain a single element which is matched against each actual array element in turn. This allows simple verification of constant array element components and coupled with RegularExpressionValueMatcher can be used to match specific array element components against a regular expression pattern. As a convenience to reduce syntactic complexity of expected string, if the expected object is not an array, a one element expected array is created containing whatever is provided as the expected value.

Some examples of typical usage idioms listed below.

Assuming JSON to be verified is held in String variable ARRAY_OF_JSONOBJECTS and contains:

{a:[{background:white,id:1,type:row}, {background:grey,id:2,type:row}, {background:white,id:3,type:row}, {background:grey,id:4,type:row}]}

then:

To verify that the 'id' attribute of first element of array 'a' is '1':

JSONComparator comparator = new DefaultComparator(JSONCompareMode.LENIENT);
Customization customization = new Customization("a", new ArrayValueMatcher<Object>(comparator, 0));
JSONAssert.assertEquals("{a:[{id:1}]}", ARRAY_OF_JSONOBJECTS, new CustomComparator(JSONCompareMode.LENIENT, customization));

To simplify complexity of expected JSON string, the value "a:[{id:1}]}" may be replaced by "a:{id:1}}"

To verify that the 'type' attribute of second and third elements of array 'a' is 'row':

JSONComparator comparator = new DefaultComparator(JSONCompareMode.LENIENT);
Customization customization = new Customization("a", new ArrayValueMatcher<Object>(comparator, 1, 2));
JSONAssert.assertEquals("{a:[{type:row}]}", ARRAY_OF_JSONOBJECTS, new CustomComparator(JSONCompareMode.LENIENT, customization));

To verify that the 'type' attribute of every element of array 'a' is 'row':

JSONComparator comparator = new DefaultComparator(JSONCompareMode.LENIENT);
Customization customization = new Customization("a", new ArrayValueMatcher<Object>(comparator));
JSONAssert.assertEquals("{a:[{type:row}]}", ARRAY_OF_JSONOBJECTS, new CustomComparator(JSONCompareMode.LENIENT, customization));

To verify that the 'id' attribute of every element of array 'a' matches regular expression '\d+'. This requires a custom comparator to specify regular expression to be used to validate each array element, hence the array of Customization instances:

// get length of array we will verify
int aLength = ((JSONArray)((JSONObject)JSONParser.parseJSON(ARRAY_OF_JSONOBJECTS)).get("a")).length();
// create array of customizations one for each array element
RegularExpressionValueMatcher<Object> regExValueMatcher = new RegularExpressionValueMatcher<Object>("\\d+"); // matches one or more digits
Customization[] customizations = new Customization[aLength];
for (int i=0; i<aLength; i++) {
String contextPath = "a["+i+"].id";
customizations[i] = new Customization(contextPath, regExValueMatcher);
}
CustomComparator regExComparator = new CustomComparator(JSONCompareMode.STRICT_ORDER, customizations);
ArrayValueMatcher<Object> regExArrayValueMatcher = new ArrayValueMatcher<Object>(regExComparator);
Customization regExArrayValueCustomization = new Customization("a", regExArrayValueMatcher);
CustomComparator regExCustomArrayValueComparator = new CustomComparator(JSONCompareMode.STRICT_ORDER, new Customization[] { regExArrayValueCustomization });
JSONAssert.assertEquals("{a:[{id:X}]}", ARRAY_OF_JSONOBJECTS, regExCustomArrayValueComparator);


To verify that the 'background' attribute of every element of array 'a' alternates between 'white' and 'grey' starting with first element 'background' being 'white':

JSONComparator comparator = new DefaultComparator(JSONCompareMode.LENIENT);
Customization customization = new Customization("a", new ArrayValueMatcher<Object>(comparator));
JSONAssert.assertEquals("{a:[{background:white},{background:grey}]}", ARRAY_OF_JSONOBJECTS, new CustomComparator(JSONCompareMode.LENIENT, customization));

Assuming JSON to be verified is held in String variable ARRAY_OF_JSONARRAYS and contains:

{a:[[6,7,8], [9,10,11], [12,13,14], [19,20,21,22]]}

then:

To verify that the first three elements of JSON array 'a' are JSON arrays of length 3:

JSONComparator comparator = new ArraySizeComparator(JSONCompareMode.STRICT_ORDER);
Customization customization = new Customization("a", new ArrayValueMatcher<Object>(comparator, 0, 2));
JSONAssert.assertEquals("{a:[[3]]}", ARRAY_OF_JSONARRAYS, new CustomComparator(JSONCompareMode.LENIENT, customization));

NOTE: simplified expected JSON strings are not possible in this case as ArraySizeComparator does not support them.

To verify that the second elements of JSON array 'a' is a JSON array whose first element has the value 9:

JSONComparator innerComparator = new DefaultComparator(JSONCompareMode.LENIENT);
Customization innerCustomization = new Customization("a[1]", new ArrayValueMatcher<Object>(innerComparator, 0));
JSONComparator comparator = new CustomComparator(JSONCompareMode.LENIENT, innerCustomization);
Customization customization = new Customization("a", new ArrayValueMatcher<Object>(comparator, 1));
JSONAssert.assertEquals("{a:[[9]]}", ARRAY_OF_JSONARRAYS, new CustomComparator(JSONCompareMode.LENIENT, customization));

To simplify complexity of expected JSON string, the value "{a:[[9]]}" may be replaced by "{a:[9]}" or "{a:9}"

Author:

Duncan Mackinder

Constructor Summary

Constructors

Constructor and Description
ArrayValueMatcher(JSONComparator comparator) Create ArrayValueMatcher to match every element in actual array against elements taken in sequence from expected array, repeating from start of expected array if necessary.
ArrayValueMatcher(JSONComparator comparator, int index) Create ArrayValueMatcher to match specified element in actual array against first element of expected array.
ArrayValueMatcher(JSONComparator comparator, int from, int to) Create ArrayValueMatcher to match every element in specified range (inclusive) from actual array against elements taken in sequence from expected array, repeating from start of expected array if necessary.

Method Summary

Modifier and Type	Method and Description
boolean	equal(String prefix, T actual, T expected, JSONCompareResult result) Match actual value with expected value.
boolean	equal(T o1, T o2)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ArrayValueMatcher

public ArrayValueMatcher(JSONComparator comparator)

Create ArrayValueMatcher to match every element in actual array against elements taken in sequence from expected array, repeating from start of expected array if necessary.

Parameters:

comparator - comparator to use to compare elements

ArrayValueMatcher

public ArrayValueMatcher(JSONComparator comparator,
                         int index)

Create ArrayValueMatcher to match specified element in actual array against first element of expected array.

Parameters:

comparator - comparator to use to compare elements

index - index of the array element to be compared

ArrayValueMatcher

public ArrayValueMatcher(JSONComparator comparator,
                         int from,
                         int to)

Create ArrayValueMatcher to match every element in specified range (inclusive) from actual array against elements taken in sequence from expected array, repeating from start of expected array if necessary.

Parameters:

comparator - comparator to use to compare elements

Method Detail

equal

public boolean equal(T o1,
                     T o2)

Specified by:

equal in interface ValueMatcher<T>

equal

public boolean equal(String prefix,
                     T actual,
                     T expected,
                     JSONCompareResult result)

Description copied from interface: LocationAwareValueMatcher

Match actual value with expected value. If match fails any of the following may occur, return false, pass failure details to specified JSONCompareResult and return true, or throw ValueMatcherException containing failure details. Passing failure details to JSONCompareResult or returning via ValueMatcherException enables more useful failure description for cases where expected value depends entirely or in part on configuration of the ValueMatcher and therefore expected value passed to this method will not give a useful indication of expected value.

Specified by:

equal in interface LocationAwareValueMatcher<T>

Parameters:

prefix - JSON path of the JSON item being tested

actual - JSON value being tested

expected - expected JSON value

result - JSONCompareResult to which match failure may be passed

Returns:

true if expected and actual equal or any difference has already been passed to specified result instance, false otherwise.