Improve tests

extras/src/main/java/com/google/gson/typeadapters/RuntimeTypeAdapterFactory.java

@@ -173,8 +173,8 @@ private RuntimeTypeAdapterFactory(Class<?> baseType, String typeFieldName, boole
   }
 
   /**
-   * Creates a new runtime type adapter using for {@code baseType} using {@code typeFieldName} as
-   * the type field name. Type field names are case sensitive.
+   * Creates a new runtime type adapter for {@code baseType} using {@code typeFieldName} as the type
+   * field name. Type field names are case sensitive.
    *
    * @param maintainType true if the type field should be included in deserialized objects
    */

extras/src/test/java/com/google/gson/interceptors/InterceptorTest.java

@@ -55,7 +55,8 @@ public void setUp() throws Exception {
 
   @Test
   public void testExceptionsPropagated() {
-    assertThrows(JsonParseException.class, () -> gson.fromJson("{}", User.class));
+    var e = assertThrows(JsonParseException.class, () -> gson.fromJson("{}", User.class));
+    assertThat(e).hasMessageThat().isEqualTo("name and password are required fields.");
   }
 
   @Test

extras/src/test/java/com/google/gson/typeadapters/UtcDateTypeAdapterTest.java

@@ -91,8 +91,8 @@ public void testWellFormedParseException() {
         assertThrows(
             JsonParseException.class, () -> gson.fromJson("2017-06-20T14:32:30", Date.class));
     assertThat(e)
-        .hasCauseThat()
         .hasMessageThat()
-        .isEqualTo("Failed to parse date ['2017-06-20T14']: 2017-06-20T14");
+        .isEqualTo(
+            "java.text.ParseException: Failed to parse date ['2017-06-20T14']: 2017-06-20T14");
   }
 }

gson/src/test/java/com/google/gson/GsonTypeAdapterTest.java

@@ -45,18 +45,20 @@ public void setUp() throws Exception {
   }
 
   @Test
-  public void testDefaultTypeAdapterThrowsParseException() throws Exception {
+  public void testDefaultTypeAdapterThrowsParseException() {
     assertThrows(JsonParseException.class, () -> gson.fromJson("{\"abc\":123}", BigInteger.class));
   }
 
   @Test
-  public void testTypeAdapterThrowsException() throws Exception {
-    assertThrows(IllegalStateException.class, () -> gson.toJson(new AtomicLong(0)));
+  public void testTypeAdapterThrowsException() {
+    Exception e = assertThrows(IllegalStateException.class, () -> gson.toJson(new AtomicLong(0)));
+    assertThat(e).isSameInstanceAs(ExceptionTypeAdapter.thrownException);
 
     // Verify that serializer is made null-safe, i.e. it is not called for null
     assertThat(gson.toJson(null, AtomicLong.class)).isEqualTo("null");
 
-    assertThrows(JsonParseException.class, () -> gson.fromJson("123", AtomicLong.class));
+    e = assertThrows(JsonParseException.class, () -> gson.fromJson("123", AtomicLong.class));
+    assertThat(e).hasCauseThat().isSameInstanceAs(ExceptionTypeAdapter.thrownException);
 
     // Verify that deserializer is made null-safe, i.e. it is not called for null
     assertThat(gson.fromJson(JsonNull.INSTANCE, AtomicLong.class)).isNull();
@@ -85,16 +87,20 @@ public void testTypeAdapterDoesNotAffectNonAdaptedTypes() {
 
   private static class ExceptionTypeAdapter
       implements JsonSerializer<AtomicLong>, JsonDeserializer<AtomicLong> {
+    @SuppressWarnings("StaticAssignmentOfThrowable")
+    static final IllegalStateException thrownException =
+        new IllegalStateException("test-exception");
+
     @Override
     public JsonElement serialize(AtomicLong src, Type typeOfSrc, JsonSerializationContext context) {
-      throw new IllegalStateException();
+      throw thrownException;
     }
 
     @Override
     public AtomicLong deserialize(
         JsonElement json, Type typeOfT, JsonDeserializationContext context)
         throws JsonParseException {
-      throw new IllegalStateException("test-exception");
+      throw thrownException;
     }
   }
 

gson/src/test/java/com/google/gson/functional/Java17RecordTest.java

@@ -144,9 +144,9 @@ record LocalRecord(String s) {
 
   /** Tests behavior when the canonical constructor throws an exception */
   @Test
-  @SuppressWarnings("StaticAssignmentOfThrowable")
   public void testThrowingConstructor() {
     record LocalRecord(String s) {
+      @SuppressWarnings("StaticAssignmentOfThrowable")
       static final RuntimeException thrownException = new RuntimeException("Custom exception");
 
       @SuppressWarnings("unused")
@@ -157,13 +157,13 @@ record LocalRecord(String s) {
 
     // TODO: Adjust this once Gson throws more specific exception type
     var e = assertThrows(RuntimeException.class, () -> gson.fromJson("{\"s\":\"value\"}", LocalRecord.class));
-      assertThat(e)
-          .hasMessageThat()
-          .isEqualTo(
-              "Failed to invoke constructor '"
-                  + LocalRecord.class.getName()
-                  + "(String)' with args [value]");
-      assertThat(e).hasCauseThat().isSameInstanceAs(LocalRecord.thrownException);
+    assertThat(e)
+        .hasMessageThat()
+        .isEqualTo(
+            "Failed to invoke constructor '"
+                + LocalRecord.class.getName()
+                + "(String)' with args [value]");
+    assertThat(e).hasCauseThat().isSameInstanceAs(LocalRecord.thrownException);
   }
 
   @Test
@@ -180,9 +180,9 @@ public String s() {
 
   /** Tests behavior when a record accessor method throws an exception */
   @Test
-  @SuppressWarnings("StaticAssignmentOfThrowable")
   public void testThrowingAccessor() {
     record LocalRecord(String s) {
+      @SuppressWarnings("StaticAssignmentOfThrowable")
       static final RuntimeException thrownException = new RuntimeException("Custom exception");
 
       @Override
@@ -192,10 +192,10 @@ public String s() {
     }
 
     var e = assertThrows(JsonIOException.class, () -> gson.toJson(new LocalRecord("a")));
-      assertThat(e)
-          .hasMessageThat()
-          .isEqualTo("Accessor method '" + LocalRecord.class.getName() + "#s()' threw exception");
-      assertThat(e).hasCauseThat().isSameInstanceAs(LocalRecord.thrownException);
+    assertThat(e)
+        .hasMessageThat()
+        .isEqualTo("Accessor method '" + LocalRecord.class.getName() + "#s()' threw exception");
+    assertThat(e).hasCauseThat().isSameInstanceAs(LocalRecord.thrownException);
   }
 
   /** Tests behavior for a record without components */

gson/src/test/java/com/google/gson/functional/JsonParserTest.java

@@ -29,6 +29,7 @@
 import com.google.gson.common.TestTypes.BagOfPrimitives;
 import com.google.gson.common.TestTypes.Nested;
 import com.google.gson.reflect.TypeToken;
+import java.io.EOFException;
 import java.io.StringReader;
 import java.lang.reflect.Type;
 import java.util.Arrays;
@@ -53,7 +54,8 @@ public void setUp() throws Exception {
 
   @Test
   public void testParseInvalidJson() {
-    assertThrows(JsonSyntaxException.class, () -> gson.fromJson("[[]", Object[].class));
+    var e = assertThrows(JsonSyntaxException.class, () -> gson.fromJson("[[]", Object[].class));
+    assertThat(e).hasCauseThat().isInstanceOf(EOFException.class);
   }
 
   @Test
@@ -131,6 +133,10 @@ public void testExtraCommasInArrays() {
   @Test
   public void testExtraCommasInMaps() {
     Type type = new TypeToken<Map<String, String>>() {}.getType();
-    assertThrows(JsonParseException.class, () -> gson.fromJson("{a:b,}", type));
+    var e = assertThrows(JsonSyntaxException.class, () -> gson.fromJson("{a:b,}", type));
+    assertThat(e)
+        .hasCauseThat()
+        .hasMessageThat()
+        .startsWith("Expected name at line 1 column 7 path $.");
   }
 }

gson/src/test/java/com/google/gson/functional/MapAsArrayTypeAdapterTest.java

@@ -66,7 +66,8 @@ public void testTwoTypesCollapseToOneSerialize() {
     original.put(1.0D, "a");
     original.put(1.0F, "b");
     Type type = new TypeToken<Map<Number, String>>() {}.getType();
-    assertThrows(JsonSyntaxException.class, () -> gson.toJson(original, type));
+    var e = assertThrows(JsonSyntaxException.class, () -> gson.toJson(original, type));
+    assertThat(e).hasMessageThat().isEqualTo("TODO");
   }
 
   @Test

gson/src/test/java/com/google/gson/functional/ObjectTest.java

@@ -43,6 +43,7 @@
 import com.google.gson.common.TestTypes.Nested;
 import com.google.gson.common.TestTypes.PrimitiveArray;
 import com.google.gson.reflect.TypeToken;
+import java.io.EOFException;
 import java.lang.reflect.Type;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -241,7 +242,8 @@ public void testEmptyStringDeserialization() {
   @Test
   public void testTruncatedDeserialization() {
     Type type = new TypeToken<List<String>>() {}.getType();
-    assertThrows(JsonParseException.class, () -> gson.fromJson("[\"a\", \"b\",", type));
+    var e = assertThrows(JsonParseException.class, () -> gson.fromJson("[\"a\", \"b\",", type));
+    assertThat(e).hasCauseThat().isInstanceOf(EOFException.class);
   }
 
   @Test
@@ -757,8 +759,8 @@ public void testThrowingDefaultConstructor() {
     assertThat(e).hasCauseThat().isSameInstanceAs(ClassWithThrowingConstructor.thrownException);
   }
 
-  @SuppressWarnings("StaticAssignmentOfThrowable")
   static class ClassWithThrowingConstructor {
+    @SuppressWarnings("StaticAssignmentOfThrowable")
     static final RuntimeException thrownException = new RuntimeException("Custom exception");
 
     public ClassWithThrowingConstructor() {

gson/src/test/java/com/google/gson/functional/PrimitiveTest.java

@@ -732,7 +732,7 @@ public void testNegativeInfinityFloatDeserialization() {
 
   @Test
   public void testBigDecimalNegativeInfinityDeserializationNotSupported() {
-    // Gson should not accept positive infinity for deserialization
+    // Gson should not accept negative infinity for deserialization
     assertThrows(JsonSyntaxException.class, () -> gson.fromJson("-Infinity", BigDecimal.class));
   }
 

gson/src/test/java/com/google/gson/functional/ReadersWritersTest.java

@@ -132,13 +132,23 @@ public void testReadWriteTwoObjects() throws IOException {
   @Test
   public void testTypeMismatchThrowsJsonSyntaxExceptionForStrings() {
     Type type = new TypeToken<Map<String, String>>() {}.getType();
-    assertThrows(JsonSyntaxException.class, () -> gson.fromJson("true", type));
+    var e = assertThrows(JsonSyntaxException.class, () -> gson.fromJson("true", type));
+    assertThat(e)
+        .hasCauseThat()
+        .hasMessageThat()
+        .startsWith("Expected BEGIN_OBJECT but was BOOLEAN");
   }
 
   @Test
   public void testTypeMismatchThrowsJsonSyntaxExceptionForReaders() {
     Type type = new TypeToken<Map<String, String>>() {}.getType();
-    assertThrows(JsonSyntaxException.class, () -> gson.fromJson(new StringReader("true"), type));
+    var e =
+        assertThrows(
+            JsonSyntaxException.class, () -> gson.fromJson(new StringReader("true"), type));
+    assertThat(e)
+        .hasCauseThat()
+        .hasMessageThat()
+        .startsWith("Expected BEGIN_OBJECT but was BOOLEAN");
   }
 
   /**

gson/src/test/java/com/google/gson/functional/StreamingTypeAdaptersTest.java

@@ -200,7 +200,6 @@ public void write(JsonWriter out, Person person) throws IOException {
     truck.passengers = new ArrayList<>();
     truck.passengers.add(null);
     truck.passengers.add(new Person("jesse", 30));
-
     assertThrows(NullPointerException.class, () -> gson.toJson(truck, Truck.class));
 
     String json = "{horsePower:1.0,passengers:[null,'jesse,30']}";

gson/src/test/java/com/google/gson/internal/bind/JsonElementReaderTest.java

@@ -262,7 +262,8 @@ public void testNextJsonElement() throws IOException {
     JsonTreeReader reader = new JsonTreeReader(element);
     reader.beginObject();
 
-    assertThrows(IllegalStateException.class, () -> reader.nextJsonElement());
+    var e = assertThrows(IllegalStateException.class, () -> reader.nextJsonElement());
+    assertThat(e).hasMessageThat().isEqualTo("Unexpected NAME when reading a JsonElement.");
     assertThat(reader.nextName()).isEqualTo("A");
     assertThat(new JsonPrimitive(1)).isEqualTo(reader.nextJsonElement());
 

gson/src/test/java/com/google/gson/stream/JsonReaderTest.java

@@ -76,7 +76,7 @@ public void testSetStrictnessNull() {
   }
 
   @Test
-  public void testEscapedNewlineNotAllowedInStrictMode() throws IOException {
+  public void testEscapedNewlineNotAllowedInStrictMode() {
     String json = "\"\\\n\"";
     JsonReader reader = new JsonReader(reader(json));
     reader.setStrictness(Strictness.STRICT);
@@ -145,7 +145,7 @@ public void testNonStrictModeParsesUnescapedControlCharacter() throws IOExceptio
   }
 
   @Test
-  public void testCapitalizedTrueFailWhenStrict() throws IOException {
+  public void testCapitalizedTrueFailWhenStrict() {
     JsonReader reader = new JsonReader(reader("TRUE"));
     reader.setStrictness(Strictness.STRICT);
 
@@ -168,7 +168,7 @@ public void testCapitalizedTrueFailWhenStrict() throws IOException {
   }
 
   @Test
-  public void testCapitalizedFalseFailWhenStrict() throws IOException {
+  public void testCapitalizedFalseFailWhenStrict() {
     JsonReader reader = new JsonReader(reader("FALSE"));
     reader.setStrictness(Strictness.STRICT);
 
@@ -191,7 +191,7 @@ public void testCapitalizedFalseFailWhenStrict() throws IOException {
   }
 
   @Test
-  public void testCapitalizedNullFailWhenStrict() throws IOException {
+  public void testCapitalizedNullFailWhenStrict() {
     JsonReader reader = new JsonReader(reader("NULL"));
     reader.setStrictness(Strictness.STRICT);
 
@@ -463,7 +463,7 @@ public void testNulls() {
   }
 
   @Test
-  public void testEmptyString() throws IOException {
+  public void testEmptyString() {
     assertThrows(EOFException.class, () -> new JsonReader(reader("")).beginArray());
     assertThrows(EOFException.class, () -> new JsonReader(reader("")).beginObject());
   }
@@ -544,7 +544,7 @@ public void testReaderDoesNotTreatU2028U2029AsNewline() throws IOException {
   }
 
   @Test
-  public void testEscapeCharacterQuoteInStrictMode() throws IOException {
+  public void testEscapeCharacterQuoteInStrictMode() {
     String json = "\"\\'\"";
     JsonReader reader = new JsonReader(reader(json));
     reader.setStrictness(Strictness.STRICT);
@@ -907,7 +907,7 @@ public void testNegativeZero() throws Exception {
 
   /**
    * This test fails because there's no double for 9223372036854775808, and our long parsing uses
-   * {@link Double#parseDouble(String)} for fractional values.
+   * Double.parseDouble() for fractional values.
    */
   @Test
   @Ignore
@@ -1371,6 +1371,10 @@ public void testStrictSemicolonDelimitedNameValuePairWithSkipValue() throws IOEx
 
   @Test
   public void testStrictUnnecessaryArraySeparators() throws IOException {
+    // The following calls `nextNull()` because a lenient JsonReader would treat redundant array
+    // separators as
+    // implicit JSON null
+
     JsonReader reader = new JsonReader(reader("[true,,true]"));
     reader.beginArray();
     assertThat(reader.nextBoolean()).isTrue();
@@ -1400,6 +1404,7 @@ public void testLenientUnnecessaryArraySeparators() throws IOException {
     reader.setStrictness(Strictness.LENIENT);
     reader.beginArray();
     assertThat(reader.nextBoolean()).isTrue();
+    // Redundant array separators are treated as implicit JSON null
     reader.nextNull();
     assertThat(reader.nextBoolean()).isTrue();
     reader.endArray();
@@ -1517,14 +1522,14 @@ public void testTopLevelValueTypeWithSkipValue() throws IOException {
   }
 
   @Test
-  public void testStrictNonExecutePrefix() throws IOException {
+  public void testStrictNonExecutePrefix() {
     JsonReader reader = new JsonReader(reader(")]}'\n []"));
     var e = assertThrows(MalformedJsonException.class, () -> reader.beginArray());
     assertStrictError(e, "line 1 column 1 path $");
   }
 
   @Test
-  public void testStrictNonExecutePrefixWithSkipValue() throws IOException {
+  public void testStrictNonExecutePrefixWithSkipValue() {
     JsonReader reader = new JsonReader(reader(")]}'\n []"));
     var e = assertThrows(MalformedJsonException.class, () -> reader.skipValue());
     assertStrictError(e, "line 1 column 1 path $");
@@ -1750,7 +1755,7 @@ public void testDeeplyNestedObjects() throws IOException {
 
   // http://code.google.com/p/google-gson/issues/detail?id=409
   @Test
-  public void testStringEndingInSlash() throws IOException {
+  public void testStringEndingInSlash() {
     JsonReader reader = new JsonReader(reader("/"));
     reader.setStrictness(Strictness.LENIENT);
     var e = assertThrows(MalformedJsonException.class, () -> reader.peek());
@@ -1762,7 +1767,7 @@ public void testStringEndingInSlash() throws IOException {
   }
 
   @Test
-  public void testDocumentWithCommentEndingInSlash() throws IOException {
+  public void testDocumentWithCommentEndingInSlash() {
     JsonReader reader = new JsonReader(reader("/* foo *//"));
     reader.setStrictness(Strictness.LENIENT);
     var e = assertThrows(MalformedJsonException.class, () -> reader.peek());
@@ -1774,7 +1779,7 @@ public void testDocumentWithCommentEndingInSlash() throws IOException {
   }
 
   @Test
-  public void testStringWithLeadingSlash() throws IOException {
+  public void testStringWithLeadingSlash() {
     JsonReader reader = new JsonReader(reader("/x"));
     reader.setStrictness(Strictness.LENIENT);
     var e = assertThrows(MalformedJsonException.class, () -> reader.peek());