Fix restoration of read base feature code.

src/main/java/htsjdk/samtools/cram/structure/CRAMRecordReadFeatures.java

@@ -28,6 +28,7 @@
 import htsjdk.samtools.CigarElement;
 import htsjdk.samtools.CigarOperator;
 import htsjdk.samtools.SAMRecord;
+import htsjdk.samtools.cram.CRAMException;
 import htsjdk.samtools.cram.build.Utils;
 import htsjdk.samtools.cram.encoding.readfeatures.*;
 import htsjdk.samtools.util.SequenceUtil;
@@ -437,30 +438,45 @@ public static byte[] restoreReadBases(
                     final InsertBase insert = (InsertBase) variation;
                     bases[posInRead++ - 1] = insert.getBase();
                     break;
-                case Bases.operator:
-                    final Bases readBases = (Bases) variation;
-                    for (byte b : readBases.getBases()) {
-                        bases[posInRead++ - 1] = b;
-                    }
-                    break;
                 case RefSkip.operator:
                     posInSeq += ((RefSkip) variation).getLength();
                     break;
+                case Bases.operator:
+                case ReadBase.operator:
+                    break; // defer until after the reference bases are retrieved
+                case Scores.operator:
+                case BaseQualityScore.operator:
+                    break; // handled by resolveQualityScores
+                case Padding.operator:
+                case HardClip.operator:
+                    break; // handled by getCigarForReadFeatures
+                default: throw new CRAMException(String.format("Unrecognized read feature code: %c", variation.getOperator()));
             }
         }
 
-        for (; posInRead <= readLength
-                && alignmentStart + posInSeq - zeroBasedReferenceOffset < referenceBases.length; posInRead++, posInSeq++) {
-            bases[posInRead - 1] = referenceBases[alignmentStart + posInSeq - zeroBasedReferenceOffset];
+        if (referenceBases != null) {
+            for (; posInRead <= readLength
+                    && alignmentStart + posInSeq - zeroBasedReferenceOffset < referenceBases.length; posInRead++, posInSeq++) {
+                bases[posInRead - 1] = referenceBases[alignmentStart + posInSeq - zeroBasedReferenceOffset];
+            }
         }
 
-        // ReadBase overwrites bases:
+        // ReadBase and Bases feature codes overwrite bases:
         for (final ReadFeature variation : variations) {
             switch (variation.getOperator()) {
                 case ReadBase.operator:
                     final ReadBase readBase = (ReadBase) variation;
                     bases[variation.getPosition() - 1] = readBase.getBase();
                     break;
+                case Bases.operator:
+                    final Bases basesOp = (Bases) variation;
+                    System.arraycopy(
+                            basesOp.getBases(),
+                            0,
+                            bases,
+                            variation.getPosition() - 1,
+                            basesOp.getBases().length);
+                    break;
                 default:
                     break;
             }

src/test/java/htsjdk/samtools/cram/structure/block/CRAMRecordReadFeaturesTest.java

@@ -3,11 +3,17 @@
 import htsjdk.HtsjdkTest;
 import htsjdk.samtools.Cigar;
 import htsjdk.samtools.SAMRecord;
+import htsjdk.samtools.SAMRecordIterator;
+import htsjdk.samtools.SamReader;
+import htsjdk.samtools.SamReaderFactory;
 import htsjdk.samtools.cram.structure.*;
 import org.testng.Assert;
 import org.testng.annotations.DataProvider;
 import org.testng.annotations.Test;
 
+import java.io.File;
+import java.io.IOException;
+
 public class CRAMRecordReadFeaturesTest extends HtsjdkTest {
 
     @DataProvider(name = "cigarTest")
@@ -35,4 +41,50 @@ public void testCigarFidelity(
         Assert.assertEquals(cigar.toString(), expectedCigarString);
     }
 
+    @DataProvider(name="readFeatureTestData")
+    private Object[][] getReadFeatureTestData() {
+        final String testDir = "src/test/resources/htsjdk/samtools/cram/";
+        return new Object[][]{
+                // cram, sam, reference (may be null)
+
+                // test CRAM file taken from the CRAM test files in hts-specs, has reads with ReadBase ('B') and
+                // Bases ('b') feature codes
+                {testDir + "0503_mapped.cram", testDir + "0503_mapped.sam", testDir + "ce.fa"},
+
+                // test CRAM file (provided as part of https://github.com/samtools/htsjdk/issues/1379) does not
+                // use reference-based compression (requires no reference) and uses Bases ('b') and SoftClip ('S')
+                // feature codes; with the sam file created from the cram via samtools
+                {testDir + "referenceNotRequired.cram", testDir + "referenceNotRequired.sam", null}
+        };
+    }
+
+    @Test(dataProvider = "readFeatureTestData")
+    private void readFeatureTest(
+            final String cramFileName,
+            final String samFileName,
+            final String referenceFileName
+    ) throws IOException {
+        // ensure these are handled correctly on read by comparing the SAMRecords created when reading the
+        // CRAM with the SAMRecords from the corresponding truth SAM (see https://github.com/samtools/htsjdk/issues/1379)
+        final File testCRAM = new File(cramFileName);
+        final File testSAM = new File(samFileName);
+        final File referenceFile = referenceFileName == null ? null : new File(referenceFileName);
+
+        try (final SamReader cramReader = SamReaderFactory.make().referenceSequence(referenceFile).open(testCRAM);
+             final SamReader samReader = SamReaderFactory.make().referenceSequence(referenceFile).open(testSAM)) {
+
+            final SAMRecordIterator cramIterator = cramReader.iterator();
+            final SAMRecordIterator samIterator = samReader.iterator();
+            while (samIterator.hasNext() && cramIterator.hasNext()) {
+                final SAMRecord samRecord = samIterator.next();
+                final SAMRecord cramRecord = cramIterator.next();
+
+                Assert.assertEquals(samRecord.getReadBases(), cramRecord.getReadBases());
+                Assert.assertEquals(samRecord.getBaseQualities(), cramRecord.getBaseQualities());
+                Assert.assertEquals(samRecord.getCigarString(), cramRecord.getCigarString());
+            }
+            Assert.assertEquals(samIterator.hasNext(), cramIterator.hasNext());
+        }
+    }
+
 }

src/test/resources/htsjdk/samtools/cram/0503_mapped.sam

@@ -0,0 +1,4 @@
+@SQ	SN:CHROMOSOME_I	LN:1009800	M5:8ede36131e0dbf3417807e48f77f3ebd	UR:/nfs/users/nfs_j/jkb/work/samtools_master/hts-specs/test/CRAM/passed/ce.fa
+@PG	ID:samtools	PN:samtools	VN:1.14	CL:samtools view -h -T src/test/resources/htsjdk/samtools/cram/ce.fa 0503_mapped.cram
+match	99	CHROMOSOME_I	1000	40	100M	=	1200	300	RTTTTTCGGGTTTTTTGAAATGAATATCGTAGCTACAGAAACGGTTGTGCACTCATCTGAAAGTTTGTTTTTCTTGTTTTCTTGCACTTTGTGCAGAATR	#############################@B?8B?BA@@DDBCDDCBC@CDCDCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC	MD:Z:0A98T0	NM:i:2
+match	147	CHROMOSOME_I	1200	40	100M	=	1000	-300	YYGTTTTAGAAAAATTATTTTTAAGAATTTTTCATTTTAGGAATATTGTTATTTCAGAAAATAGCTAAATGTGATTTCTGTAATTTTGCCTGCCAAAGYY	#############################@B?8B?BA@@DDBCDDCBC@CDCDCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC	MD:Z:0T0T0T94T0T0C0	NM:i:6