#97 - Json 파일 출력기 구현

`.json` 형식으로 파일을 출력해주는 기능을 추가한다.

src/main/java/uno/fastcampus/testdata/domain/constant/ExportFileType.java

@@ -3,7 +3,7 @@
 public enum ExportFileType {
     CSV,
     TSV,
-//    JSON, // TODO: 강의 시간 상 구현을 생략함. 구현하면 TODO 삭제
+    JSON,
 //    SQL_INSERT, // TODO: 강의 시간 상 구현을 생략함. 구현하면 TODO 삭제
     ;
 }

src/main/java/uno/fastcampus/testdata/service/exporter/JsonFileExporter.java

@@ -0,0 +1,57 @@
+package uno.fastcampus.testdata.service.exporter;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Component;
+import uno.fastcampus.testdata.domain.constant.ExportFileType;
+import uno.fastcampus.testdata.dto.SchemaFieldDto;
+import uno.fastcampus.testdata.dto.TableSchemaDto;
+import uno.fastcampus.testdata.service.generator.MockDataGeneratorContext;
+
+import java.util.*;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+@Slf4j
+@RequiredArgsConstructor
+@Component
+public class JsonFileExporter implements MockDataFileExporter {
+
+    private final MockDataGeneratorContext mockDataGeneratorContext;
+    private final ObjectMapper mapper;
+
+    @Override
+    public ExportFileType getType() {
+        return ExportFileType.JSON;
+    }
+
+    @Override
+    public String export(TableSchemaDto dto, Integer rowCount) {
+        try {
+            List<Map<String, Object>> list = new ArrayList<>();
+
+            IntStream.range(0, rowCount).forEach(i -> {
+                Map<String, Object> map = new LinkedHashMap<>();
+                dto.schemaFields().stream()
+                        .sorted(Comparator.comparing(SchemaFieldDto::fieldOrder))
+                        .forEach(field -> {
+                            map.put(field.fieldName(), mockDataGeneratorContext.generate(
+                                    field.mockDataType(),
+                                    field.blankPercent(),
+                                    field.typeOptionJson(),
+                                    field.forceValue()
+                            ));
+                        });
+                list.add(map);
+            });
+
+            return mapper.writeValueAsString(list);
+        } catch (JsonProcessingException e) {
+            log.warn("테이블 스키마 데이터를 JSON으로 변환하는데 실패했습니다 - {}", dto, e);
+            return "";
+        }
+    }
+
+}

src/test/java/uno/fastcampus/testdata/service/exporter/JsonFileExporterTest.java

@@ -0,0 +1,95 @@
+package uno.fastcampus.testdata.service.exporter;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.Spy;
+import org.mockito.junit.jupiter.MockitoExtension;
+import uno.fastcampus.testdata.domain.constant.ExportFileType;
+import uno.fastcampus.testdata.domain.constant.MockDataType;
+import uno.fastcampus.testdata.dto.SchemaFieldDto;
+import uno.fastcampus.testdata.dto.TableSchemaDto;
+import uno.fastcampus.testdata.service.generator.MockDataGeneratorContext;
+
+import java.util.Set;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.BDDMockito.*;
+import static org.mockito.Mockito.times;
+
+@DisplayName("[Logic] Json 파일 출력기 테스트")
+@ExtendWith(MockitoExtension.class)
+class JsonFileExporterTest {
+
+    @InjectMocks private JsonFileExporter sut;
+
+    @Mock private MockDataGeneratorContext mockDataGeneratorContext;
+    @Spy private ObjectMapper mapper;
+
+    @DisplayName("이 파일 출력기의 유형은 JSON이다.")
+    @Test
+    void givenNothing_whenCheckingType_thenReturnsJsonType() {
+        // Given
+
+        // When & Then
+        assertThat(sut.getType()).isEqualTo(ExportFileType.JSON);
+    }
+
+    @DisplayName("테이블 스키마 정보와 행 수가 주어지면, JSON 형식의 문자열을 생성한다.")
+    @Test
+    void givenSchemaAndRowCount_whenExporting_thenReturnsJsonFormattedString() throws Exception {
+        // Given
+        TableSchemaDto dto = TableSchemaDto.of(
+                "test_schema",
+                "uno",
+                null,
+                Set.of(
+                        SchemaFieldDto.of("id", MockDataType.ROW_NUMBER, 1, 0, null, null),
+                        SchemaFieldDto.of("name", MockDataType.NAME, 2, 0, null, null),
+                        SchemaFieldDto.of("created_at", MockDataType.DATETIME, 5, 0, null, null),
+                        SchemaFieldDto.of("age", MockDataType.NUMBER, 3, 0, null, null),
+                        SchemaFieldDto.of("car", MockDataType.CAR, 4, 0, null, null)
+                )
+        );
+        int rowCount = 10;
+        given(mockDataGeneratorContext.generate(any(), any(), any(), any())).willReturn("test-value");
+
+        // When
+        String result = sut.export(dto, rowCount);
+
+        // Then
+        System.out.println(result); // 관찰용
+        assertThat(result)
+                .startsWith("[")
+                .endsWith("]")
+                .contains("""
+                        {"id":"test-value","name":"test-value","age":"test-value","car":"test-value","created_at":"test-value"}"""
+                );
+        then(mockDataGeneratorContext).should(times(rowCount * dto.schemaFields().size())).generate(any(), any(), any(), any());
+        then(mapper).should().writeValueAsString(any());
+    }
+
+    @DisplayName("JSON 변환에 실패하면, 빈 문자열을 반환한다.")
+    @Test
+    void givenSchemaAndRowCount_whenFailingToJsonFormatting_thenReturnsEmptyString() throws Exception {
+        // Given
+        TableSchemaDto dto = TableSchemaDto.of("test_schema", "uno", null, Set.of(SchemaFieldDto.of("id", MockDataType.ROW_NUMBER, 1, 0, null, null)));
+        int rowCount = 10;
+        given(mockDataGeneratorContext.generate(any(), any(), any(), any())).willReturn("test-value");
+        willThrow(JsonProcessingException.class).given(mapper).writeValueAsString(any());
+
+        // When
+        String result = sut.export(dto, rowCount);
+
+        // Then
+        assertThat(result).isEqualTo("");
+        then(mockDataGeneratorContext).should(times(rowCount * dto.schemaFields().size())).generate(any(), any(), any(), any());
+        then(mapper).should().writeValueAsString(any());
+    }
+
+}