SPRING.md

Spring and kjson-test

Many users will seek to use kjson-test in conjunction with the Spring Framework. The following suggestion may assist with the use of kjson-test with Spring's MockMvc.

Testing with MockMvc

Spring includes functions to simplify access to the MockMvc class, taking advantage of Kotlin's DSL capabilities. These can be extended to make use of kjson-test.

A class similar to the following will allow kjson-test tests to be integrated easily into MockMvc testing:

package my.example

import io.kjson.test.JSONExpect
import org.hamcrest.BaseMatcher
import org.hamcrest.Description
import org.springframework.test.web.servlet.result.ContentResultMatchersDsl

class JSONMatcher(private val tests: JSONExpect.() -> Unit) : BaseMatcher<String>() {

    override fun matches(actual: Any?): Boolean {
        if (actual !is String)
            return false
        JSONExpect.expectJSON(actual, tests)
        return true
    }

    override fun describeTo(description: Description) {
        description.appendText("valid JSON")
    }

    companion object {
        fun ContentResultMatchersDsl.matchesJSON(tests: JSONExpect.() -> Unit) = string(JSONMatcher(tests))
    }

}

Now, a test can be coded as follows:

        mockMvc.get("/path/to/be/tested") {
            accept(MediaType.APPLICATION_JSON)
        }.andExpect {
            status { isOk() }
            content {
                matchesJSON {
                    property("accountID", "ABC123")
                    property("accountName", "Test account")
                    // etc.
                }
            }
        }

This class is provided as documentation rather than as a source file because it would not be practical for this project to include the dependencies required to resolve the Spring references.

2021-10-11