A couple more tests

src/test/java/io/deephaven/csv/CsvReaderTest.java

@@ -27,6 +27,7 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.Timeout;
 import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 import org.junit.jupiter.params.provider.ValueSource;
 
 import java.io.*;
@@ -1978,6 +1979,73 @@ public void fixedColumnWidthsShortRows(boolean allowMissingColumns) throws CsvRe
         }
     }
 
+    /**
+     * If there is no header row, the caller needs to specify column widths.
+     */
+    @ParameterizedTest
+    @ValueSource(booleans = {false, true})
+    public void noHeaderRowRequiresFixColumnWidthsSpecified(boolean specifyColumnWidths) throws CsvReaderException {
+        final String input =
+                ""
+                        + "GOOG  Dividend 0.25    200\n"
+                        + "T     Dividend 0.15    300\n"
+                        + "Z     Coupon   0.18    500\n";
+
+        final ColumnSet expected =
+                ColumnSet.of(
+                        Column.ofRefs("Column1", "GOOG", "T", "Z"),
+                        Column.ofRefs("Column2", "Dividend", "Dividend", "Coupon"),
+                        Column.ofValues("Column3", 0.25, 0.15, 0.18),
+                        Column.ofValues("Column4", 200, 300, 500));
+
+        final CsvSpecs.Builder specsBase = defaultCsvBuilder().hasFixedWidthColumns(true).hasHeaderRow(false)
+                .delimiter(' ').ignoreSurroundingSpaces(true);
+
+        if (specifyColumnWidths) {
+            final CsvSpecs specs = specsBase.fixedColumnWidths(Arrays.asList(6, 9, 8, 3)).build();
+            invokeTest(specs, input, expected);
+        } else {
+            final CsvSpecs specs = specsBase.build();
+            Assertions.assertThatThrownBy(() -> invokeTest(specs, input, expected))
+                    .hasMessage("Can't proceed because hasHeaderRow is false but fixedColumnWidths is unspecified");
+        }
+    }
+
+    /**
+     * If there is no header row, the caller may specify column names. Otherwise synthetic column names  will be
+     * generated.
+     */
+    @ParameterizedTest
+    @ValueSource(booleans = {false, true})
+    public void columnNamesMayBeSpecified(boolean specifyColumnNames) throws CsvReaderException {
+        final String input =
+                ""
+                        + "GOOG  Dividend 0.25    200\n"
+                        + "T     Dividend 0.15    300\n"
+                        + "Z     Coupon   0.18    500\n";
+
+        final String[] expectedColumnNames = specifyColumnNames ?
+                new String[]{"Sym", "Type", "Price", "SecurityId"} :
+                new String[]{"Column1", "Column2", "Column3", "Column4"};
+
+
+        final ColumnSet expected =
+                ColumnSet.of(
+                        Column.ofRefs(expectedColumnNames[0], "GOOG", "T", "Z"),
+                        Column.ofRefs(expectedColumnNames[1], "Dividend", "Dividend", "Coupon"),
+                        Column.ofValues(expectedColumnNames[2], 0.25, 0.15, 0.18),
+                        Column.ofValues(expectedColumnNames[3], 200, 300, 500));
+
+        CsvSpecs.Builder specsBuilder = defaultCsvBuilder().hasFixedWidthColumns(true).hasHeaderRow(false)
+                .delimiter(' ').ignoreSurroundingSpaces(true).fixedColumnWidths(Arrays.asList(6, 9, 8, 3));
+
+        if (specifyColumnNames) {
+            specsBuilder = specsBuilder.headers(Arrays.asList(expectedColumnNames));
+        }
+
+        invokeTest(specsBuilder.build(), input, expected);
+    }
+
     /**
      * All six Unicode characters ♡♥❥❦◑╳ are in the Basic Multilingual Plane and can all be represented with a single
      * Java char. Therefore, they are counted the same with both counting conventions.