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vkryachkoBrian Chen
vkryachko
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Brian Chen
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Implement encoder context nesting. (#1018)
* Implement encoder context nesting. * Update api.txt * Fix double-nested issue.
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‎encoders/firebase-encoders/api.txt

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@@ -20,6 +20,7 @@ package com.google.firebase.encoders {
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method @NonNull public com.google.firebase.encoders.ObjectEncoderContext add(@NonNull String, int) throws com.google.firebase.encoders.EncodingException;
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method @NonNull public com.google.firebase.encoders.ObjectEncoderContext add(@NonNull String, long) throws com.google.firebase.encoders.EncodingException;
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method @NonNull public com.google.firebase.encoders.ObjectEncoderContext add(@NonNull String, boolean) throws com.google.firebase.encoders.EncodingException;
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method @NonNull public com.google.firebase.encoders.ObjectEncoderContext nested(@NonNull String);
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}
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public interface ValueEncoder<T> {

‎encoders/firebase-encoders/src/main/java/com/google/firebase/encoders/ObjectEncoderContext.java

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@@ -68,4 +68,28 @@ ObjectEncoderContext add(@NonNull String name, double value)
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@NonNull
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ObjectEncoderContext add(@NonNull String name, boolean value)
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throws IOException, EncodingException;
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/**
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* Begin a nested JSON object.
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*
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* <p>Unlike {@code add()} methods, this method returns a new "child" context that's used to
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* populate the nested JSON object. This context can only be used until the parent context is
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* mutated by calls to {@code add()} or {@code nested()}, violating this will result in a {@link
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* IllegalStateException}.
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*
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* <p>Nesting can be arbitrarily deep.
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*
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* <p>Example:
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*
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* <pre>{@code
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* ctx.add("key", "value");
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* ObjectEncoderContext nested = ctx.nested("nested");
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* nested.add("key", "value");
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*
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* // After this call the above nested context is invalid.
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* ctx.add("anotherKey", 1);
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* }</pre>
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*/
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@NonNull
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ObjectEncoderContext nested(@NonNull String name) throws IOException;
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}

‎encoders/firebase-encoders/src/main/java/com/google/firebase/encoders/json/JsonValueObjectEncoderContext.java

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@@ -30,6 +30,8 @@
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final class JsonValueObjectEncoderContext implements ObjectEncoderContext, ValueEncoderContext {
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private JsonValueObjectEncoderContext childContext = null;
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private boolean active = true;
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private final JsonWriter jsonWriter;
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private final Map<Class<?>, ObjectEncoder<?>> objectEncoders;
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private final Map<Class<?>, ValueEncoder<?>> valueEncoders;
@@ -43,10 +45,17 @@ final class JsonValueObjectEncoderContext implements ObjectEncoderContext, Value
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this.valueEncoders = valueEncoders;
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}
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private JsonValueObjectEncoderContext(JsonValueObjectEncoderContext anotherContext) {
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this.jsonWriter = anotherContext.jsonWriter;
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this.objectEncoders = anotherContext.objectEncoders;
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this.valueEncoders = anotherContext.valueEncoders;
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}
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@NonNull
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@Override
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public JsonValueObjectEncoderContext add(@NonNull String name, @Nullable Object o)
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throws IOException, EncodingException {
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maybeUnNest();
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jsonWriter.name(name);
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if (o == null) {
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jsonWriter.nullValue();
@@ -59,6 +68,7 @@ public JsonValueObjectEncoderContext add(@NonNull String name, @Nullable Object
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@Override
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public JsonValueObjectEncoderContext add(@NonNull String name, double value)
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throws IOException, EncodingException {
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maybeUnNest();
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jsonWriter.name(name);
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return add(value);
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}
@@ -67,6 +77,7 @@ public JsonValueObjectEncoderContext add(@NonNull String name, double value)
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@Override
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public JsonValueObjectEncoderContext add(@NonNull String name, int value)
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throws IOException, EncodingException {
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maybeUnNest();
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jsonWriter.name(name);
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return add(value);
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}
@@ -75,6 +86,7 @@ public JsonValueObjectEncoderContext add(@NonNull String name, int value)
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@Override
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public JsonValueObjectEncoderContext add(@NonNull String name, long value)
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throws IOException, EncodingException {
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maybeUnNest();
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jsonWriter.name(name);
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return add(value);
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}
@@ -83,42 +95,58 @@ public JsonValueObjectEncoderContext add(@NonNull String name, long value)
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@Override
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public JsonValueObjectEncoderContext add(@NonNull String name, boolean value)
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throws IOException, EncodingException {
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maybeUnNest();
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jsonWriter.name(name);
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return add(value);
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}
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@NonNull
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@Override
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public ObjectEncoderContext nested(@NonNull String name) throws IOException {
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maybeUnNest();
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childContext = new JsonValueObjectEncoderContext(this);
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jsonWriter.name(name);
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jsonWriter.beginObject();
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return childContext;
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}
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@NonNull
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@Override
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public JsonValueObjectEncoderContext add(@Nullable String value)
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throws IOException, EncodingException {
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maybeUnNest();
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jsonWriter.value(value);
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return this;
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}
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@NonNull
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@Override
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public JsonValueObjectEncoderContext add(double value) throws IOException, EncodingException {
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maybeUnNest();
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jsonWriter.value(value);
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return this;
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}
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@NonNull
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@Override
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public JsonValueObjectEncoderContext add(int value) throws IOException, EncodingException {
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maybeUnNest();
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jsonWriter.value(value);
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return this;
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}
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@NonNull
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@Override
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public JsonValueObjectEncoderContext add(long value) throws IOException, EncodingException {
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maybeUnNest();
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jsonWriter.value(value);
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return this;
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}
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@NonNull
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@Override
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public JsonValueObjectEncoderContext add(boolean value) throws IOException, EncodingException {
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maybeUnNest();
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jsonWriter.value(value);
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return this;
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}
@@ -127,6 +155,7 @@ public JsonValueObjectEncoderContext add(boolean value) throws IOException, Enco
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@Override
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public JsonValueObjectEncoderContext add(@Nullable byte[] bytes)
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throws IOException, EncodingException {
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maybeUnNest();
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if (bytes == null) {
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jsonWriter.nullValue();
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} else {
@@ -237,6 +266,20 @@ JsonValueObjectEncoderContext add(@Nullable Object o) throws IOException, Encodi
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}
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void close() throws IOException {
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maybeUnNest();
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jsonWriter.flush();
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}
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private void maybeUnNest() throws IOException {
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if (!active) {
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throw new IllegalStateException(
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"Parent context used since this context was created. Cannot use this context anymore.");
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}
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if (childContext != null) {
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childContext.maybeUnNest();
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childContext.active = false;
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childContext = null;
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jsonWriter.endObject();
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}
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}
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}

‎encoders/firebase-encoders/src/test/java/com/google/firebase/encoders/json/JsonValueObjectEncoderContextTest.java

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@@ -25,6 +25,7 @@
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import com.google.firebase.encoders.DataEncoder;
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import com.google.firebase.encoders.EncodingException;
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import com.google.firebase.encoders.ObjectEncoder;
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import com.google.firebase.encoders.ObjectEncoderContext;
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import com.google.firebase.encoders.ValueEncoder;
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import java.io.IOException;
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import java.io.Writer;
@@ -386,4 +387,62 @@ public void testEncoderError() throws IOException, EncodingException {
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.build()
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.encode(DummyClass.INSTANCE, mockWriter));
388389
}
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@Test
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public void testNested_whenUsedCorrectly_shouldProduceNestedJson() throws EncodingException {
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ObjectEncoder<DummyClass> objectEncoder =
394+
(o, ctx) -> {
395+
ctx.add("name", "value");
396+
ctx.nested("nested1").add("key1", "value1");
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ctx.add("after1", true);
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ctx.nested("nested2").add("key2", "value2");
399+
ctx.add("after2", true);
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};
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String result =
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new JsonDataEncoderBuilder()
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.registerEncoder(DummyClass.class, objectEncoder)
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.build()
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.encode(DummyClass.INSTANCE);
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assertThat(result)
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.isEqualTo(
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"{\"name\":\"value\",\"nested1\":{\"key1\":\"value1\"},"
411+
+ "\"after1\":true,\"nested2\":{\"key2\":\"value2\"},\"after2\":true}");
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}
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@Test
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public void testTwiceNested_whenUsedCorrectly_shouldProduceNestedJson() throws EncodingException {
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ObjectEncoder<DummyClass> objectEncoder =
417+
(o, ctx) -> {
418+
ctx.add("name", "value");
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ctx.nested("nested1").add("key1", "value1").nested("nested2");
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ctx.add("after1", true);
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};
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String result =
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new JsonDataEncoderBuilder()
425+
.registerEncoder(DummyClass.class, objectEncoder)
426+
.build()
427+
.encode(DummyClass.INSTANCE);
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assertThat(result)
430+
.isEqualTo(
431+
"{\"name\":\"value\",\"nested1\":{\"key1\":\"value1\",\"nested2\":{}},\"after1\":true}");
432+
}
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@Test
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public void testNested_whenUsedAfterParent_shouldThrow() {
436+
ObjectEncoder<DummyClass> objectEncoder =
437+
(o, ctx) -> {
438+
ObjectEncoderContext nested = ctx.nested("nested1");
439+
ctx.add("after1", true);
440+
nested.add("hello", "world");
441+
};
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DataEncoder encoder =
444+
new JsonDataEncoderBuilder().registerEncoder(DummyClass.class, objectEncoder).build();
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assertThrows(IllegalStateException.class, () -> encoder.encode(DummyClass.INSTANCE));
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}
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}

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