Initialize reason and SQLState in PostgresqlServerErrorException.

src/main/java/io/r2dbc/postgresql/PostgresqlServerErrorException.java

@@ -97,29 +97,30 @@ public final class PostgresqlServerErrorException extends R2dbcException {
      * @throws NullPointerException if {@code fields} is {@code null}
      */
     public PostgresqlServerErrorException(List<Field> fields) {
-        Objects.requireNonNull(fields, "fields must not be null");
-
-        Map<FieldType, String> map = fields.stream()
-            .collect(Collectors.toMap(Field::getType, Field::getValue));
+        this(convertToMap(fields));
+    }
 
-        this.code = map.get(CODE);
-        this.columnName = map.get(COLUMN_NAME);
-        this.constraintName = map.get(CONSTRAINT_NAME);
-        this.dataTypeName = map.get(DATA_TYPE_NAME);
-        this.detail = map.get(DETAIL);
-        this.file = map.get(FILE);
-        this.hint = map.get(HINT);
-        this.internalPosition = map.get(INTERNAL_POSITION);
-        this.internalQuery = map.get(INTERNAL_QUERY);
-        this.line = map.get(LINE);
-        this.message = map.get(MESSAGE);
-        this.position = map.get(POSITION);
-        this.routine = map.get(ROUTINE);
-        this.schemaName = map.get(SCHEMA_NAME);
-        this.severityLocalized = map.get(SEVERITY_LOCALIZED);
-        this.severityNonLocalized = map.get(SEVERITY_NON_LOCALIZED);
-        this.tableName = map.get(TABLE_NAME);
-        this.where = map.get(WHERE);
+    private PostgresqlServerErrorException(Map<FieldType, String> fields) {
+        super(fields.get(MESSAGE), fields.get(CODE));
+
+        this.code = fields.get(CODE);
+        this.columnName = fields.get(COLUMN_NAME);
+        this.constraintName = fields.get(CONSTRAINT_NAME);
+        this.dataTypeName = fields.get(DATA_TYPE_NAME);
+        this.detail = fields.get(DETAIL);
+        this.file = fields.get(FILE);
+        this.hint = fields.get(HINT);
+        this.internalPosition = fields.get(INTERNAL_POSITION);
+        this.internalQuery = fields.get(INTERNAL_QUERY);
+        this.line = fields.get(LINE);
+        this.message = fields.get(MESSAGE);
+        this.position = fields.get(POSITION);
+        this.routine = fields.get(ROUTINE);
+        this.schemaName = fields.get(SCHEMA_NAME);
+        this.severityLocalized = fields.get(SEVERITY_LOCALIZED);
+        this.severityNonLocalized = fields.get(SEVERITY_NON_LOCALIZED);
+        this.tableName = fields.get(TABLE_NAME);
+        this.where = fields.get(WHERE);
     }
 
     @Override
@@ -352,6 +353,13 @@ static void handleErrorResponse(BackendMessage message, SynchronousSink<BackendM
         }
     }
 
+    private static Map<FieldType, String> convertToMap(List<Field> fields) {
+        Objects.requireNonNull(fields, "fields must not be null");
+
+        return fields.stream()
+            .collect(Collectors.toMap(Field::getType, Field::getValue));
+    }
+
     private static PostgresqlServerErrorException toException(ErrorResponse errorResponse) {
         Objects.requireNonNull(errorResponse, "errorResponse must not be null");
 

src/test/java/io/r2dbc/postgresql/PostgresqlServerErrorExceptionTest.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2017-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.r2dbc.postgresql;
+
+import io.r2dbc.postgresql.message.backend.Field;
+import org.junit.jupiter.api.Test;
+
+import java.util.Collections;
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+final class PostgresqlServerErrorExceptionTest {
+
+    @Test
+    void initializesSqlState() {
+
+        List<Field> fields = Collections.singletonList(new Field(Field.FieldType.CODE, "1234"));
+
+        PostgresqlServerErrorException exception = new PostgresqlServerErrorException(fields);
+
+        assertThat(exception.getSqlState()).isEqualTo("1234");
+    }
+
+    @Test
+    void initializesReason() {
+
+        List<Field> fields = Collections.singletonList(new Field(Field.FieldType.MESSAGE, "Duplicate"));
+
+        PostgresqlServerErrorException exception = new PostgresqlServerErrorException(fields);
+
+        assertThat(exception.getMessage()).isEqualTo("Duplicate");
+    }
+
+    @Test
+    void skipsInitializationWithEmptyFields() {
+
+        PostgresqlServerErrorException exception = new PostgresqlServerErrorException(Collections.emptyList());
+
+        assertThat(exception.getSqlState()).isNull();
+        assertThat(exception.getMessage()).isNull();
+    }
+}