feat: support json body in OAuth2HttpRequest

src/main/kotlin/no/nav/security/mock/oauth2/extensions/String.kt

@@ -1,5 +1,7 @@
 package no.nav.security.mock.oauth2.extensions
 
+import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
+import com.fasterxml.jackson.module.kotlin.readValue
 import java.net.URLDecoder
 import java.nio.charset.StandardCharsets
 
@@ -13,3 +15,5 @@ internal fun String.keyValuesToMap(listDelimiter: String): Map<String, String> =
         }
 
 internal fun String.urlDecode(): String = URLDecoder.decode(this, StandardCharsets.UTF_8)
+
+internal fun String.parseJson(): Map<String, String> = jacksonObjectMapper().readValue(this)

src/main/kotlin/no/nav/security/mock/oauth2/http/OAuth2HttpRequest.kt

@@ -16,6 +16,7 @@ import no.nav.security.mock.oauth2.extensions.toJwksUrl
 import no.nav.security.mock.oauth2.extensions.toRevocationEndpointUrl
 import no.nav.security.mock.oauth2.extensions.toTokenEndpointUrl
 import no.nav.security.mock.oauth2.extensions.toUserInfoUrl
+import no.nav.security.mock.oauth2.extensions.parseJson
 import no.nav.security.mock.oauth2.grant.TokenExchangeGrant
 import no.nav.security.mock.oauth2.missingParameter
 import okhttp3.Headers
@@ -28,7 +29,7 @@ data class OAuth2HttpRequest(
     val body: String? = null,
 ) {
     val url: HttpUrl get() = proxyAwareUrl()
-    val formParameters: Parameters = Parameters(body)
+    val formParameters: Parameters = Parameters(body, headers["Content-Type"])
     val cookies: Map<String, String> = headers["Cookie"]?.keyValuesToMap(";") ?: emptyMap()
 
     fun asTokenExchangeRequest(): TokenRequest {
@@ -136,8 +137,12 @@ data class OAuth2HttpRequest(
 
     data class Parameters(
         val parameterString: String?,
+        val contentType: String?
     ) {
-        val map: Map<String, String> = parameterString?.keyValuesToMap("&") ?: emptyMap()
+        val map: Map<String, String> = when (contentType) {
+            "application/json" -> parameterString?.parseJson() ?: emptyMap()
+            else -> parameterString?.keyValuesToMap("&") ?: emptyMap()
+        }
 
         fun get(name: String): String? = map[name]
     }

src/main/kotlin/no/nav/security/mock/oauth2/templates/TemplateMapper.kt

@@ -26,7 +26,7 @@ class TemplateMapper(
                             .query(null)
                             .build()
                             .toString(),
-                    "query" to OAuth2HttpRequest.Parameters(oAuth2HttpRequest.url.query).map,
+                    "query" to OAuth2HttpRequest.Parameters(oAuth2HttpRequest.url.query, null).map,
                 ),
             ),
         )
@@ -69,7 +69,7 @@ class TemplateMapper(
                 mapOf(
                     "url" to urlWithoutQuery,
                     "token_url" to url.toTokenEndpointUrl(),
-                    "query" to OAuth2HttpRequest.Parameters(url.query).map,
+                    "query" to OAuth2HttpRequest.Parameters(url.query, null).map,
                     "client_auth_method" to clientAuthMethod,
                 ),
             ),

src/test/kotlin/no/nav/security/mock/oauth2/http/OAuth2HttpRequestTest.kt

@@ -218,4 +218,29 @@ internal class OAuth2HttpRequestTest {
         req1.toWellKnown().tokenEndpoint shouldBe "http://localhost:8080/mypath/token"
         req1.toWellKnown().jwksUri shouldBe "http://localhost:8080/mypath/jwks"
     }
+
+    @Test
+    fun `form parameters should be parsed from urlencoded string or json`() {
+        val urlEncodedRequest = OAuth2HttpRequest(
+            headers = Headers.headersOf("Content-Type", "application/x-www-form-urlencoded"),
+            method = "POST",
+            originalUrl = "http://localhost/token".toHttpUrl(),
+            body = "grant_type=client_credentials&scope=test"
+        )
+        urlEncodedRequest.formParameters.map shouldBe mapOf(
+            "grant_type" to "client_credentials",
+            "scope" to "test"
+        )
+
+        val jsonRequest = OAuth2HttpRequest(
+            headers = Headers.headersOf("Content-Type", "application/json"),
+            method = "POST",
+            originalUrl = "http://localhost/token".toHttpUrl(),
+            body = """{"grant_type": "client_credentials", "scope": "test"}"""
+        )
+        jsonRequest.formParameters.map shouldBe mapOf(
+            "grant_type" to "client_credentials",
+            "scope" to "test"
+        )
+    }
 }