fixed bug for M2 GGA alleles with zero coverage

src/main/java/org/broadinstitute/hellbender/tools/walkers/mutect/SomaticGenotypingEngine.java

@@ -256,8 +256,8 @@ private void addGenotypes(final LikelihoodMatrix<Allele> tumorLog10Matrix,
         final int dp = (int) MathUtils.sum(adArray);
         final GenotypeBuilder gb = new GenotypeBuilder(tumorSample, tumorLog10Matrix.alleles());
         final double[] flatPriorPseudocounts = new IndexRange(0, tumorLog10Matrix.numberOfAlleles()).mapToDouble(n -> 1);
-        final double[] alleleFractionsPosterior = SomaticLikelihoodsEngine.alleleFractionsPosterior(
-                getAsRealMatrix(tumorLog10Matrix), flatPriorPseudocounts);
+        final double[] alleleFractionsPosterior = tumorLog10Matrix.numberOfReads() == 0 ? flatPriorPseudocounts :
+                SomaticLikelihoodsEngine.alleleFractionsPosterior(getAsRealMatrix(tumorLog10Matrix), flatPriorPseudocounts);
         if (!MTAC.calculateAFfromAD) {
             // Use mean of the allele fraction posterior distribution
             double[] tumorAlleleFractionsMean = MathUtils.normalizeFromRealSpace(alleleFractionsPosterior);

src/test/java/org/broadinstitute/hellbender/tools/walkers/mutect/Mutect2IntegrationTest.java

@@ -318,7 +318,7 @@ public void testGivenAllelesMode() throws Exception {
         final List<String> args = Arrays.asList("-I", NA12878_20_21_WGS_bam,
                 "-" + M2ArgumentCollection.TUMOR_SAMPLE_SHORT_NAME, "NA12878",
                 "-R", b37_reference_20_21,
-                "-L", "20:10000000-10010000",
+                "-L", "20:9998500-10010000",
                 "-O", unfilteredVcf.getAbsolutePath(),
                 "--genotyping-mode", "GENOTYPE_GIVEN_ALLELES",
                 "--alleles", givenAllelesVcf.getAbsolutePath());
@@ -332,6 +332,25 @@ public void testGivenAllelesMode() throws Exception {
         }
     }
 
+    // make sure that GGA mode with given alleles that normally wouldn't be called due to complete lack of coverage
+    // doesn't run into any edge case bug involving empty likelihoods matrices
+    @Test
+    public void testGivenAllelesZeroCoverage() throws Exception {
+        Utils.resetRandomGenerator();
+        final File bam = new File(DREAM_BAMS_DIR, "tumor_3.bam");
+        final String sample = "IS3.snv.indel.sv";
+        final File unfilteredVcf = createTempFile("unfiltered", ".vcf");
+        final File givenAllelesVcf = new File(toolsTestDir, "mutect/gga_mode_2.vcf");
+        final List<String> args = Arrays.asList("-I", bam.getAbsolutePath(),
+                "-" + M2ArgumentCollection.TUMOR_SAMPLE_SHORT_NAME, sample,
+                "-R", b37_reference_20_21,
+                "-L", "20:1119000-1120000",
+                "-O", unfilteredVcf.getAbsolutePath(),
+                "--genotyping-mode", "GENOTYPE_GIVEN_ALLELES",
+                "--alleles", givenAllelesVcf.getAbsolutePath());
+        runCommandLine(args);
+    }
+
     @Test
     public void testContaminationFilter() throws Exception {
         Utils.resetRandomGenerator();

src/test/resources/org/broadinstitute/hellbender/tools/mutect/gga_mode_2.vcf

@@ -0,0 +1,30 @@
+##fileformat=VCFv4.2
+##FILTER=<ID=LowQual,Description="Low quality">
+##FORMAT=<ID=AD,Number=R,Type=Integer,Description="Allelic depths for the ref and alt alleles in the order listed">
+##FORMAT=<ID=DP,Number=1,Type=Integer,Description="Approximate read depth (reads with MQ=255 or with bad mates are filtered)">
+##FORMAT=<ID=GQ,Number=1,Type=Integer,Description="Genotype Quality">
+##FORMAT=<ID=GT,Number=1,Type=String,Description="Genotype">
+##FORMAT=<ID=PL,Number=G,Type=Integer,Description="Normalized, Phred-scaled likelihoods for genotypes as defined in the VCF specification">
+##INFO=<ID=AC,Number=A,Type=Integer,Description="Allele count in genotypes, for each ALT allele, in the same order as listed">
+##INFO=<ID=AF,Number=A,Type=Float,Description="Allele Frequency, for each ALT allele, in the same order as listed">
+##INFO=<ID=AN,Number=1,Type=Integer,Description="Total number of alleles in called genotypes">
+##INFO=<ID=BaseQRankSum,Number=1,Type=Float,Description="Z-score from Wilcoxon rank sum test of Alt Vs. Ref base qualities">
+##INFO=<ID=ClippingRankSum,Number=1,Type=Float,Description="Z-score From Wilcoxon rank sum test of Alt vs. Ref number of hard clipped bases">
+##INFO=<ID=DP,Number=1,Type=Integer,Description="Approximate read depth; some reads may have been filtered">
+##INFO=<ID=DS,Number=0,Type=Flag,Description="Were any of the samples downsampled?">
+##INFO=<ID=ExcessHet,Number=1,Type=Float,Description="Phred-scaled p-value for exact test of excess heterozygosity">
+##INFO=<ID=FS,Number=1,Type=Float,Description="Phred-scaled p-value using Fisher's exact test to detect strand bias">
+##INFO=<ID=InbreedingCoeff,Number=1,Type=Float,Description="Inbreeding coefficient as estimated from the genotype likelihoods per-sample when compared against the Hardy-Weinberg expectation">
+##INFO=<ID=MLEAC,Number=A,Type=Integer,Description="Maximum likelihood expectation (MLE) for the allele counts (not necessarily the same as the AC), for each ALT allele, in the same order as listed">
+##INFO=<ID=MLEAF,Number=A,Type=Float,Description="Maximum likelihood expectation (MLE) for the allele frequency (not necessarily the same as the AF), for each ALT allele, in the same order as listed">
+##INFO=<ID=MQ,Number=1,Type=Float,Description="RMS Mapping Quality">
+##INFO=<ID=MQRankSum,Number=1,Type=Float,Description="Z-score From Wilcoxon rank sum test of Alt vs. Ref read mapping qualities">
+##INFO=<ID=QD,Number=1,Type=Float,Description="Variant Confidence/Quality by Depth">
+##INFO=<ID=RAW_MQ,Number=1,Type=Float,Description="Raw data for RMS Mapping Quality">
+##INFO=<ID=ReadPosRankSum,Number=1,Type=Float,Description="Z-score from Wilcoxon rank sum test of Alt vs. Ref read position bias">
+##INFO=<ID=SOR,Number=1,Type=Float,Description="Symmetric Odds Ratio of 2x2 contingency table to detect strand bias">
+##contig=<ID=20,length=63025520>
+##contig=<ID=21,length=48129895>
+#CHROM	POS	ID	REF	ALT	QUAL	FILTER	INFO
+20	1119886	.	A	T	.	.	.
+20	1119950	.	A	T	.	.	.