Add and cleanup tests based on review feedback

* Add tests to verify the DefaultJwtParserBuilder will correctly wrap Deserializer implementations
* Cleanup string handling in JwtDeserializerTest

Author: bdemers

impl/src/test/groovy/io/jsonwebtoken/impl/DefaultJwtParserBuilderTest.groovy

@@ -16,17 +16,21 @@
 package io.jsonwebtoken.impl
 
 import com.fasterxml.jackson.databind.ObjectMapper
+import io.jsonwebtoken.JwtParser
 import io.jsonwebtoken.Jwts
 import io.jsonwebtoken.SignatureAlgorithm
 import io.jsonwebtoken.io.Decoder
 import io.jsonwebtoken.io.DecodingException
 import io.jsonwebtoken.io.DeserializationException
 import io.jsonwebtoken.io.Deserializer
 import io.jsonwebtoken.security.Keys
+import org.hamcrest.CoreMatchers
 import org.junit.Test
 
+import static org.easymock.EasyMock.niceMock
 import static org.junit.Assert.assertEquals
 import static org.junit.Assert.assertSame
+import static org.hamcrest.MatcherAssert.assertThat
 
 // NOTE to the casual reader: even though this test class appears mostly empty, the DefaultJwtParserBuilder
 // implementation is tested to 100% coverage.  The vast majority of its tests are in the JwtsTest class.  This class
@@ -92,4 +96,25 @@ class DefaultJwtParserBuilderTest {
             assertEquals DefaultJwtParserBuilder.MAX_CLOCK_SKEW_ILLEGAL_MSG, expected.message
         }
     }
+
+    @Test
+    void testDefaultDecoder() {
+        JwtParser parser = new DefaultJwtParserBuilder().build()
+        assertThat parser.jwtParser.deserializer, CoreMatchers.instanceOf(JwtDeserializer)
+
+        // TODO: When the ImmutableJwtParser replaces the default implementation this test will need updating, something like:
+        // assertThat parser.deserializer, CoreMatchers.instanceOf(JwtDeserializer)
+    }
+
+    @Test
+    void testUserSetDecoderWrapsImplementation() {
+        Deserializer deserializer = niceMock(Deserializer)
+        JwtParser parser = new DefaultJwtParserBuilder()
+            .deserializeJsonWith(deserializer)
+            .build()
+
+        // TODO: When the ImmutableJwtParser replaces the default implementation this test will need updating
+        assertThat parser.jwtParser.deserializer, CoreMatchers.instanceOf(JwtDeserializer)
+        assertSame deserializer, parser.jwtParser.deserializer.deserializer
+    }
 }

impl/src/test/groovy/io/jsonwebtoken/impl/JwtDeserializerTest.groovy

@@ -38,7 +38,8 @@ class JwtDeserializerTest {
     @Test
     void testParserStackOverflowError() {
 
-        byte[] jsonBytes = '{"test": "testParserStackOverflowError"}'.getBytes(StandardCharsets.UTF_8)
+        String json = '{"test": "testParserStackOverflowError"}'
+        byte[] jsonBytes = json.getBytes(StandardCharsets.UTF_8)
 
         // create a Deserializer that will throw a StackOverflowError
         Deserializer<Map<String,?>> deserializer = mock(Deserializer)
@@ -49,7 +50,7 @@ class JwtDeserializerTest {
             new JwtDeserializer<>(deserializer).deserialize(jsonBytes)
             Assert.fail("Expected IOException")
         } catch (IOException e) {
-            assertEquals JwtDeserializer.MALFORMED_COMPLEX_ERROR + new String(jsonBytes), e.message
+            assertEquals JwtDeserializer.MALFORMED_COMPLEX_ERROR + json, e.message
         }
     }
 
@@ -59,7 +60,8 @@ class JwtDeserializerTest {
     @Test
     void testDeserializationExceptionMessage() {
 
-        byte[] jsonBytes = '{"test": "testDeserializationExceptionMessage"}'.getBytes(StandardCharsets.UTF_8)
+        String json = '{"test": "testDeserializationExceptionMessage"}'
+        byte[] jsonBytes = json.getBytes(StandardCharsets.UTF_8)
 
         // create a Deserializer that will throw a DeserializationException
         Deserializer<Map<String,?>> deserializer = mock(Deserializer)
@@ -70,7 +72,7 @@ class JwtDeserializerTest {
             new JwtDeserializer<>(deserializer).deserialize(jsonBytes)
             Assert.fail("Expected MalformedJwtException")
         } catch (MalformedJwtException e) {
-            assertEquals JwtDeserializer.MALFORMED_ERROR + new String(jsonBytes), e.message
+            assertEquals JwtDeserializer.MALFORMED_ERROR + json, e.message
         }
     }
 }