fix: broken CSV cell by backslash escaped quoteChar

src/main/java/com/treasure_data/td_import/reader/CSVRecordReader.java

@@ -197,14 +197,30 @@ public boolean readColumns(final List<String> columns) throws IOException {
                         currentRow.append(line); // update untokenized CSV row
                         line += NEWLINE; // add newline to simplify parsing
                     } else if (c == quoteChar) {
+                        /*
+                         * Removes following buggy behavior. TODO: delete this code and comment.
+                         *
+                         * - If the source CSV stream includes [\"] sequence in quoted column, it fails to detect end of column.
+                         *   ex. "abc\","def" should be parsed as [abc\], [def] but it was [abc"def...]
+                         *
+                         * New code no longer behaves like this.
+                         *
                         if (charIndex > 2 && line.charAt(charIndex - 2) == '\\'
                                 && line.charAt(charIndex - 1) == '\\') {
+                            // ****************************************************
+                            // * This means [\\"] -> [\\] and moves new column.   *
+                            // * It's the same behavior with 'else'. Unnecessary. *
+                            // ****************************************************
                             state = TokenizerState.NORMAL;
                             quoteScopeStartingLine = -1;
                         } else if (charIndex > 1 && line.charAt(charIndex - 1) == '\\') {
+                            // ********************************************
+                            // * This means [\"] -> [\"] and keep parsing *
+                            // ********************************************
                             currentColumn.append(c);
                             //charIndex++;
-                        } else if (line.charAt(charIndex + 1) == quoteChar) {
+                        } else */
+                        if (line.charAt(charIndex + 1) == quoteChar) {
                             /*
                              * An escaped quote (""). Add a single quote, then
                              * move the cursor so the next iteration of the loop

src/test/java/com/treasure_data/td_import/reader/TestCSVFileReader.java

@@ -241,6 +241,31 @@ public void assertContextEquals(TestCSVFileReader test) {
         }
     }
 
+    public static class Context07 implements Context {
+        public void createContext(TestCSVFileReader test)
+                throws Exception {
+            test.columnNames = new String[] { "time", "string1", "string2" };
+            test.columnTypes = new ColumnType[] { ColumnType.LONG, ColumnType.STRING, ColumnType.STRING };
+        }
+
+        public String generateCSVText(TestCSVFileReader test) {
+            StringBuilder sbuf = new StringBuilder();
+            sbuf.append(test.columnNames[0]).append(COMMA);
+            sbuf.append(test.columnNames[1]).append(COMMA);
+            sbuf.append(test.columnNames[2]).append(LF);
+            sbuf.append("\"12345\"").append(COMMA);
+            sbuf.append("\"str\"\"ing\\\\\"").append(COMMA);
+            sbuf.append("\"str\"\"ing\\\"").append(LF);
+            return sbuf.toString();
+        }
+
+        public void assertContextEquals(TestCSVFileReader test) {
+            assertArrayEquals(test.columnNames, test.reader.getColumnNames());
+            assertArrayEquals(test.columnTypes, test.reader.getColumnTypes());
+            assertTrue(test.reader.getSkipColumns().isEmpty());
+        }
+    }
+
     protected String fileName = "./file.csv";
     protected int numLine;
 
@@ -398,6 +423,17 @@ public void checkContextWhenReaderConfigurationWithTimeFormat() throws Exception
         checkContextWhenReaderConfiguration(context);
     }
 
+    @Test
+    public void checkContextWhenColumnEndsWithBackslash() throws Exception {
+        Context07 context = new Context07();
+
+        createPrepareConfiguration();
+        createFileWriter();
+        createFileReader();
+
+        checkContextWhenReaderConfiguration(context);
+    }
+
     private void checkContextWhenReaderConfiguration(Context context) throws Exception {
         // create context
         context.createContext(this);