Add JsonTest

documentation-support/src/test/java/tech/picnic/errorprone/documentation/JsonTest.java

@@ -0,0 +1,62 @@
+package tech.picnic.errorprone.documentation;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.google.auto.value.AutoValue;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+final class JsonTest {
+  private static final TestObject TEST_OBJECT = new AutoValue_JsonTest_TestObject("foo", 42);
+  private static final String TEST_JSON = "{\"string\":\"foo\",\"number\":42}";
+
+  @Test
+  void write(@TempDir Path directory) {
+    Path file = directory.resolve("test.json");
+
+    Json.write(file, TEST_OBJECT);
+
+    assertThat(file).content(UTF_8).isEqualTo(TEST_JSON);
+  }
+
+  @Test
+  void writeFailure(@TempDir Path directory) {
+    assertThatThrownBy(() -> Json.write(directory, TEST_OBJECT))
+        .isInstanceOf(UncheckedIOException.class)
+        .hasMessageContaining("Failure writing to '%s'", directory)
+        .hasCauseInstanceOf(FileNotFoundException.class);
+  }
+
+  @Test
+  void read(@TempDir Path directory) throws IOException {
+    Path file = directory.resolve("test.json");
+
+    Files.writeString(file, TEST_JSON, UTF_8);
+
+    assertThat(Json.read(file, TestObject.class)).isEqualTo(TEST_OBJECT);
+  }
+
+  @Test
+  void readFailure(@TempDir Path directory) {
+    assertThatThrownBy(() -> Json.read(directory, TestObject.class))
+        .isInstanceOf(UncheckedIOException.class)
+        .hasMessageContaining("Failure reading from '%s'", directory)
+        .hasCauseInstanceOf(FileNotFoundException.class);
+  }
+
+  @AutoValue
+  @JsonDeserialize(as = AutoValue_JsonTest_TestObject.class)
+  abstract static class TestObject {
+    abstract String string();
+
+    abstract int number();
+  }
+}