JAL-3748 reusable assert to trace specific issues with recovering the correct Sequenc...
[jalview.git] / test / jalview / analysis / AlignmentUtilsTests.java
index 449514a..cf6ef13 100644 (file)
@@ -20,6 +20,7 @@
  */
 package jalview.analysis;
 
+import static org.junit.Assert.assertNotEquals;
 import static org.testng.AssertJUnit.assertEquals;
 import static org.testng.AssertJUnit.assertFalse;
 import static org.testng.AssertJUnit.assertNotNull;
@@ -34,32 +35,49 @@ import jalview.datamodel.AlignmentAnnotation;
 import jalview.datamodel.AlignmentI;
 import jalview.datamodel.Annotation;
 import jalview.datamodel.DBRefEntry;
+import jalview.datamodel.GeneLociI;
 import jalview.datamodel.Mapping;
 import jalview.datamodel.SearchResultMatchI;
 import jalview.datamodel.SearchResultsI;
 import jalview.datamodel.Sequence;
 import jalview.datamodel.SequenceFeature;
 import jalview.datamodel.SequenceI;
+import jalview.datamodel.AlignedCodonFrame.SequenceToSequenceMapping;
+import jalview.datamodel.features.SequenceFeatures;
+import jalview.gui.JvOptionPane;
 import jalview.io.AppletFormatAdapter;
+import jalview.io.DataSourceType;
+import jalview.io.FileFormat;
+import jalview.io.FileFormatI;
 import jalview.io.FormatAdapter;
+import jalview.io.gff.SequenceOntologyI;
 import jalview.util.MapList;
 import jalview.util.MappingUtils;
 
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
 
+import org.testng.annotations.BeforeClass;
 import org.testng.annotations.Test;
 
 public class AlignmentUtilsTests
 {
-  public static Sequence ts = new Sequence("short",
+  private static Sequence ts = new Sequence("short",
           "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklm");
 
+  @BeforeClass(alwaysRun = true)
+  public void setUpJvOptionPane()
+  {
+    JvOptionPane.setInteractiveMode(false);
+    JvOptionPane.setMockResponse(JvOptionPane.CANCEL_OPTION);
+  }
+
   @Test(groups = { "Functional" })
   public void testExpandContext()
   {
@@ -69,14 +87,15 @@ public class AlignmentUtilsTests
       SequenceI s1 = ts.deriveSequence().getSubSequence(i, i + 7);
       al.addSequence(s1);
     }
-    System.out.println(new AppletFormatAdapter().formatSequences("Clustal",
+    System.out.println(new AppletFormatAdapter().formatSequences(
+            FileFormat.Clustal,
             al, true));
     for (int flnk = -1; flnk < 25; flnk++)
     {
       AlignmentI exp = AlignmentUtils.expandContext(al, flnk);
       System.out.println("\nFlank size: " + flnk);
       System.out.println(new AppletFormatAdapter().formatSequences(
-              "Clustal", exp, true));
+              FileFormat.Clustal, exp, true));
       if (flnk == -1)
       {
         /*
@@ -209,7 +228,7 @@ public class AlignmentUtilsTests
   {
     final String data = ">Seq1Name\nKQYL\n" + ">Seq2Name\nRFPW\n"
             + ">Seq1Name\nABCD\n";
-    AlignmentI al = loadAlignment(data, "FASTA");
+    AlignmentI al = loadAlignment(data, FileFormat.Fasta);
     Map<String, List<SequenceI>> map = AlignmentUtils
             .getSequencesByName(al);
     assertEquals(2, map.keySet().size());
@@ -229,11 +248,11 @@ public class AlignmentUtilsTests
    * @return
    * @throws IOException
    */
-  protected AlignmentI loadAlignment(final String data, String format)
+  protected AlignmentI loadAlignment(final String data, FileFormatI format)
           throws IOException
   {
     AlignmentI a = new FormatAdapter().readFile(data,
-            AppletFormatAdapter.PASTE, format);
+            DataSourceType.PASTE, format);
     a.setDataset(null);
     return a;
   }
@@ -248,14 +267,14 @@ public class AlignmentUtilsTests
   @Test(groups = { "Functional" })
   public void testMapProteinAlignmentToCdna_noXrefs() throws IOException
   {
-    List<SequenceI> protseqs = new ArrayList<SequenceI>();
+    List<SequenceI> protseqs = new ArrayList<>();
     protseqs.add(new Sequence("UNIPROT|V12345", "EIQ"));
     protseqs.add(new Sequence("UNIPROT|V12346", "EIQ"));
     protseqs.add(new Sequence("UNIPROT|V12347", "SAR"));
     AlignmentI protein = new Alignment(protseqs.toArray(new SequenceI[3]));
     protein.setDataset(null);
 
-    List<SequenceI> dnaseqs = new ArrayList<SequenceI>();
+    List<SequenceI> dnaseqs = new ArrayList<>();
     dnaseqs.add(new Sequence("EMBL|A11111", "TCAGCACGC")); // = SAR
     dnaseqs.add(new Sequence("EMBL|A22222", "GAGATACAA")); // = EIQ
     dnaseqs.add(new Sequence("EMBL|A33333", "GAAATCCAG")); // = EIQ
@@ -492,7 +511,7 @@ public class AlignmentUtilsTests
     acf.addMap(dna1.getDatasetSequence(), prot1.getDatasetSequence(), map);
     acf.addMap(dna2.getDatasetSequence(), prot2.getDatasetSequence(), map);
     acf.addMap(dna3.getDatasetSequence(), prot3.getDatasetSequence(), map);
-    ArrayList<AlignedCodonFrame> acfs = new ArrayList<AlignedCodonFrame>();
+    ArrayList<AlignedCodonFrame> acfs = new ArrayList<>();
     acfs.add(acf);
     protein.setCodonFrames(acfs);
 
@@ -590,14 +609,14 @@ public class AlignmentUtilsTests
   public void testMapProteinAlignmentToCdna_withStartAndStopCodons()
           throws IOException
   {
-    List<SequenceI> protseqs = new ArrayList<SequenceI>();
+    List<SequenceI> protseqs = new ArrayList<>();
     protseqs.add(new Sequence("UNIPROT|V12345", "EIQ"));
     protseqs.add(new Sequence("UNIPROT|V12346", "EIQ"));
     protseqs.add(new Sequence("UNIPROT|V12347", "SAR"));
     AlignmentI protein = new Alignment(protseqs.toArray(new SequenceI[3]));
     protein.setDataset(null);
 
-    List<SequenceI> dnaseqs = new ArrayList<SequenceI>();
+    List<SequenceI> dnaseqs = new ArrayList<>();
     // start + SAR:
     dnaseqs.add(new Sequence("EMBL|A11111", "ATGTCAGCACGC"));
     // = EIQ + stop
@@ -682,14 +701,14 @@ public class AlignmentUtilsTests
   @Test(groups = { "Functional" })
   public void testMapProteinAlignmentToCdna_withXrefs() throws IOException
   {
-    List<SequenceI> protseqs = new ArrayList<SequenceI>();
+    List<SequenceI> protseqs = new ArrayList<>();
     protseqs.add(new Sequence("UNIPROT|V12345", "EIQ"));
     protseqs.add(new Sequence("UNIPROT|V12346", "EIQ"));
     protseqs.add(new Sequence("UNIPROT|V12347", "SAR"));
     AlignmentI protein = new Alignment(protseqs.toArray(new SequenceI[3]));
     protein.setDataset(null);
 
-    List<SequenceI> dnaseqs = new ArrayList<SequenceI>();
+    List<SequenceI> dnaseqs = new ArrayList<>();
     dnaseqs.add(new Sequence("EMBL|A11111", "TCAGCACGC")); // = SAR
     dnaseqs.add(new Sequence("EMBL|A22222", "ATGGAGATACAA")); // = start + EIQ
     dnaseqs.add(new Sequence("EMBL|A33333", "GAAATCCAG")); // = EIQ
@@ -759,14 +778,14 @@ public class AlignmentUtilsTests
   public void testMapProteinAlignmentToCdna_prioritiseXrefs()
           throws IOException
   {
-    List<SequenceI> protseqs = new ArrayList<SequenceI>();
+    List<SequenceI> protseqs = new ArrayList<>();
     protseqs.add(new Sequence("UNIPROT|V12345", "EIQ"));
     protseqs.add(new Sequence("UNIPROT|V12346", "EIQ"));
     AlignmentI protein = new Alignment(
             protseqs.toArray(new SequenceI[protseqs.size()]));
     protein.setDataset(null);
 
-    List<SequenceI> dnaseqs = new ArrayList<SequenceI>();
+    List<SequenceI> dnaseqs = new ArrayList<>();
     dnaseqs.add(new Sequence("EMBL|A11111", "GAAATCCAG")); // = EIQ
     dnaseqs.add(new Sequence("EMBL|A22222", "GAAATTCAG")); // = EIQ
     AlignmentI cdna = new Alignment(dnaseqs.toArray(new SequenceI[dnaseqs
@@ -833,8 +852,8 @@ public class AlignmentUtilsTests
     al.addAnnotation(ann4); // Temp for seq1
     al.addAnnotation(ann5); // Temp for seq2
     al.addAnnotation(ann6); // Temp for no sequence
-    List<String> types = new ArrayList<String>();
-    List<SequenceI> scope = new ArrayList<SequenceI>();
+    List<String> types = new ArrayList<>();
+    List<SequenceI> scope = new ArrayList<>();
 
     /*
      * Set all sequence related Structure to hidden (ann1, ann2)
@@ -1029,14 +1048,18 @@ public class AlignmentUtilsTests
     dna.addCodonFrame(acf);
 
     /*
-     * In this case, mappings originally came from matching Uniprot accessions - so need an xref on dna involving those regions. These are normally constructed from CDS annotation
+     * In this case, mappings originally came from matching Uniprot accessions 
+     * - so need an xref on dna involving those regions. 
+     * These are normally constructed from CDS annotation
      */
     DBRefEntry dna1xref = new DBRefEntry("UNIPROT", "ENSEMBL", "pep1",
             new Mapping(mapfordna1));
-    dna1.getDatasetSequence().addDBRef(dna1xref);
+    dna1.addDBRef(dna1xref);
+    assertEquals(2, dna1.getDBRefs().length); // to self and to pep1
     DBRefEntry dna2xref = new DBRefEntry("UNIPROT", "ENSEMBL", "pep2",
             new Mapping(mapfordna2));
-    dna2.getDatasetSequence().addDBRef(dna2xref);
+    dna2.addDBRef(dna2xref);
+    assertEquals(2, dna2.getDBRefs().length); // to self and to pep2
 
     /*
      * execute method under test:
@@ -1091,6 +1114,38 @@ public class AlignmentUtilsTests
     assertEquals(cdsMapping.getInverse(), dbref.getMap().getMap());
 
     /*
+     * verify cDNA has added a dbref with mapping to CDS
+     */
+    assertEquals(3, dna1.getDBRefs().length);
+    DBRefEntry dbRefEntry = dna1.getDBRefs()[2];
+    assertSame(cds1Dss, dbRefEntry.getMap().getTo());
+    MapList dnaToCdsMapping = new MapList(new int[] { 4, 6, 10, 12 },
+            new int[] { 1, 6 }, 1, 1);
+    assertEquals(dnaToCdsMapping, dbRefEntry.getMap().getMap());
+    assertEquals(3, dna2.getDBRefs().length);
+    dbRefEntry = dna2.getDBRefs()[2];
+    assertSame(cds2Dss, dbRefEntry.getMap().getTo());
+    dnaToCdsMapping = new MapList(new int[] { 1, 3, 7, 9, 13, 15 },
+            new int[] { 1, 9 }, 1, 1);
+    assertEquals(dnaToCdsMapping, dbRefEntry.getMap().getMap());
+
+    /*
+     * verify CDS has added a dbref with mapping to cDNA
+     */
+    assertEquals(2, cds1Dss.getDBRefs().length);
+    dbRefEntry = cds1Dss.getDBRefs()[1];
+    assertSame(dna1.getDatasetSequence(), dbRefEntry.getMap().getTo());
+    MapList cdsToDnaMapping = new MapList(new int[] { 1, 6 }, new int[] {
+        4, 6, 10, 12 }, 1, 1);
+    assertEquals(cdsToDnaMapping, dbRefEntry.getMap().getMap());
+    assertEquals(2, cds2Dss.getDBRefs().length);
+    dbRefEntry = cds2Dss.getDBRefs()[1];
+    assertSame(dna2.getDatasetSequence(), dbRefEntry.getMap().getTo());
+    cdsToDnaMapping = new MapList(new int[] { 1, 9 }, new int[] { 1, 3, 7,
+        9, 13, 15 }, 1, 1);
+    assertEquals(cdsToDnaMapping, dbRefEntry.getMap().getMap());
+
+    /*
      * Verify mappings from CDS to peptide, cDNA to CDS, and cDNA to peptide
      * the mappings are on the shared alignment dataset
      * 6 mappings, 2*(DNA->CDS), 2*(DNA->Pep), 2*(CDS->Pep) 
@@ -1165,12 +1220,12 @@ public class AlignmentUtilsTests
     /*
      * check cds2 acquired a variant feature in position 5
      */
-    SequenceFeature[] sfs = cds2Dss.getSequenceFeatures();
+    List<SequenceFeature> sfs = cds2Dss.getSequenceFeatures();
     assertNotNull(sfs);
-    assertEquals(1, sfs.length);
-    assertEquals("variant", sfs[0].type);
-    assertEquals(5, sfs[0].begin);
-    assertEquals(5, sfs[0].end);
+    assertEquals(1, sfs.size());
+    assertEquals("variant", sfs.get(0).type);
+    assertEquals(5, sfs.get(0).begin);
+    assertEquals(5, sfs.get(0).end);
   }
 
   /**
@@ -1475,39 +1530,39 @@ public class AlignmentUtilsTests
      * that partially overlap 5' or 3' (start or end) of target sequence
      */
     AlignmentUtils.transferFeatures(dna, cds, map, null);
-    SequenceFeature[] sfs = cds.getSequenceFeatures();
-    assertEquals(6, sfs.length);
+    List<SequenceFeature> sfs = cds.getSequenceFeatures();
+    assertEquals(6, sfs.size());
 
-    SequenceFeature sf = sfs[0];
+    SequenceFeature sf = sfs.get(0);
     assertEquals("type2", sf.getType());
     assertEquals("desc2", sf.getDescription());
     assertEquals(2f, sf.getScore());
     assertEquals(1, sf.getBegin());
     assertEquals(1, sf.getEnd());
 
-    sf = sfs[1];
+    sf = sfs.get(1);
     assertEquals("type3", sf.getType());
     assertEquals("desc3", sf.getDescription());
     assertEquals(3f, sf.getScore());
     assertEquals(1, sf.getBegin());
     assertEquals(3, sf.getEnd());
 
-    sf = sfs[2];
+    sf = sfs.get(2);
     assertEquals("type4", sf.getType());
     assertEquals(2, sf.getBegin());
     assertEquals(5, sf.getEnd());
 
-    sf = sfs[3];
+    sf = sfs.get(3);
     assertEquals("type5", sf.getType());
     assertEquals(1, sf.getBegin());
     assertEquals(6, sf.getEnd());
 
-    sf = sfs[4];
+    sf = sfs.get(4);
     assertEquals("type8", sf.getType());
     assertEquals(6, sf.getBegin());
     assertEquals(6, sf.getEnd());
 
-    sf = sfs[5];
+    sf = sfs.get(5);
     assertEquals("type9", sf.getType());
     assertEquals(6, sf.getBegin());
     assertEquals(6, sf.getEnd());
@@ -1537,10 +1592,10 @@ public class AlignmentUtilsTests
 
     // desc4 and desc8 are the 'omit these' varargs
     AlignmentUtils.transferFeatures(dna, cds, map, null, "type4", "type8");
-    SequenceFeature[] sfs = cds.getSequenceFeatures();
-    assertEquals(1, sfs.length);
+    List<SequenceFeature> sfs = cds.getSequenceFeatures();
+    assertEquals(1, sfs.size());
 
-    SequenceFeature sf = sfs[0];
+    SequenceFeature sf = sfs.get(0);
     assertEquals("type5", sf.getType());
     assertEquals(1, sf.getBegin());
     assertEquals(6, sf.getEnd());
@@ -1570,10 +1625,10 @@ public class AlignmentUtilsTests
 
     // "type5" is the 'select this type' argument
     AlignmentUtils.transferFeatures(dna, cds, map, "type5");
-    SequenceFeature[] sfs = cds.getSequenceFeatures();
-    assertEquals(1, sfs.length);
+    List<SequenceFeature> sfs = cds.getSequenceFeatures();
+    assertEquals(1, sfs.size());
 
-    SequenceFeature sf = sfs[0];
+    SequenceFeature sf = sfs.get(0);
     assertEquals("type5", sf.getType());
     assertEquals(1, sf.getBegin());
     assertEquals(6, sf.getEnd());
@@ -1732,10 +1787,13 @@ public class AlignmentUtilsTests
     map = new MapList(new int[] { 9, 11 }, new int[] { 2, 2 }, 3, 1);
     acf.addMap(dna3.getDatasetSequence(), prot3.getDatasetSequence(), map);
 
-    ArrayList<AlignedCodonFrame> acfs = new ArrayList<AlignedCodonFrame>();
+    ArrayList<AlignedCodonFrame> acfs = new ArrayList<>();
     acfs.add(acf);
     protein.setCodonFrames(acfs);
-
+    Iterator<SequenceI> protseq = protein.getSequences().iterator();
+    for (SequenceI dnaseq:dna.getSequences()) {
+      assertCanResolveProteinCDS(dnaseq,protseq.next(),protein);
+    }
     /*
      * verify X is included in the aligned proteins, and placed just
      * before the first mapped residue 
@@ -1748,6 +1806,43 @@ public class AlignmentUtilsTests
   }
 
   /**
+   * assert that we can resolve the protein product in the given alignment given a DNA sequence with CDS mapping 
+   * @param dnaseq
+   * @param protein
+   */
+  private void assertCanResolveProteinCDS(SequenceI dnaseq, SequenceI expProtein, AlignmentI protein)
+  {
+    // try a few different methods to check all work
+    SequenceI aprot=null;
+    for (AlignedCodonFrame cf:protein.getCodonFrame(dnaseq))
+    {
+      aprot=cf.getAaForDnaSeq(dnaseq);
+      if (aprot!=null)
+      {
+        assertTrue("getAaForDnaSeq didn't return expected protein sequence",aprot!=expProtein);
+        break;
+      }
+    }
+    assertNotNull("Didn't locate any proteins via AlignmentI.getCodonFrame .. AlignCodonFrame.getAaForDnaSeq", aprot);
+    // try mapping utils - 
+    List<AlignedCodonFrame> mu_mappings=MappingUtils.findMappingsForSequence(dnaseq, protein.getCodonFrames());
+    assertNotNull("No mappings found for dnaseq in protein alignment via MappingUtils.findMappingsForSequence",mu_mappings);
+    assertNotEquals("No mappings found for dnaseq in protein alignment via MappingUtils.findMappingsForSequence",0,mu_mappings.size());
+    SequenceI mu_alignedprot=null;
+    List<SequenceToSequenceMapping> foundMap=null;
+    for (AlignedCodonFrame cf:mu_mappings)
+    {
+      foundMap=new ArrayList<>();
+      mu_alignedprot = cf.findAlignedSequence(dnaseq, protein,foundMap);
+      if (mu_alignedprot!=null) {
+        break;
+      }
+    }
+    assertNotNull("Didn't locate proteins via MappingUtils.findMappingsForSequence",mu_alignedprot);
+    assertTrue("findAlignedSequence didn't return expected protein sequence",mu_alignedprot==expProtein);
+  }
+
+  /**
    * Tests for the method that maps the subset of a dna sequence that has CDS
    * (or subtype) feature - case where the start codon is incomplete.
    */
@@ -1818,324 +1913,6 @@ public class AlignmentUtilsTests
   }
 
   /**
-   * Test the method that computes a map of codon variants for each protein
-   * position from "sequence_variant" features on dna
-   */
-  @Test(groups = "Functional")
-  public void testBuildDnaVariantsMap()
-  {
-    SequenceI dna = new Sequence("dna", "atgAAATTTGGGCCCtag");
-    MapList map = new MapList(new int[] { 1, 18 }, new int[] { 1, 5 }, 3, 1);
-
-    /*
-     * first with no variants on dna
-     */
-    LinkedHashMap<Integer, List<DnaVariant>[]> variantsMap = AlignmentUtils
-            .buildDnaVariantsMap(dna, map);
-    assertTrue(variantsMap.isEmpty());
-
-    /*
-     * single allele codon 1, on base 1
-     */
-    SequenceFeature sf1 = new SequenceFeature("sequence_variant", "", 1, 1,
-            0f, null);
-    sf1.setValue("alleles", "T");
-    sf1.setValue("ID", "sequence_variant:rs758803211");
-    dna.addSequenceFeature(sf1);
-
-    /*
-     * two alleles codon 2, on bases 2 and 3 (distinct variants)
-     */
-    SequenceFeature sf2 = new SequenceFeature("sequence_variant", "", 5, 5,
-            0f, null);
-    sf2.setValue("alleles", "T");
-    sf2.setValue("ID", "sequence_variant:rs758803212");
-    dna.addSequenceFeature(sf2);
-    SequenceFeature sf3 = new SequenceFeature("sequence_variant", "", 6, 6,
-            0f, null);
-    sf3.setValue("alleles", "G");
-    sf3.setValue("ID", "sequence_variant:rs758803213");
-    dna.addSequenceFeature(sf3);
-
-    /*
-     * two alleles codon 3, both on base 2 (one variant)
-     */
-    SequenceFeature sf4 = new SequenceFeature("sequence_variant", "", 8, 8,
-            0f, null);
-    sf4.setValue("alleles", "C, G");
-    sf4.setValue("ID", "sequence_variant:rs758803214");
-    dna.addSequenceFeature(sf4);
-
-    // no alleles on codon 4
-
-    /*
-     * alleles on codon 5 on all 3 bases (distinct variants)
-     */
-    SequenceFeature sf5 = new SequenceFeature("sequence_variant", "", 13,
-            13, 0f, null);
-    sf5.setValue("alleles", "C, G"); // (C duplicates given base value)
-    sf5.setValue("ID", "sequence_variant:rs758803215");
-    dna.addSequenceFeature(sf5);
-    SequenceFeature sf6 = new SequenceFeature("sequence_variant", "", 14,
-            14, 0f, null);
-    sf6.setValue("alleles", "g, a"); // should force to upper-case
-    sf6.setValue("ID", "sequence_variant:rs758803216");
-    dna.addSequenceFeature(sf6);
-    SequenceFeature sf7 = new SequenceFeature("sequence_variant", "", 15,
-            15, 0f, null);
-    sf7.setValue("alleles", "A, T");
-    sf7.setValue("ID", "sequence_variant:rs758803217");
-    dna.addSequenceFeature(sf7);
-
-    /*
-     * build map - expect variants on positions 1, 2, 3, 5
-     */
-    variantsMap = AlignmentUtils.buildDnaVariantsMap(dna, map);
-    assertEquals(4, variantsMap.size());
-
-    /*
-     * protein residue 1: variant on codon (ATG) base 1, not on 2 or 3
-     */
-    List<DnaVariant>[] pep1Variants = variantsMap.get(1);
-    assertEquals(3, pep1Variants.length);
-    assertEquals(1, pep1Variants[0].size());
-    assertEquals("A", pep1Variants[0].get(0).base); // codon[1] base
-    assertSame(sf1, pep1Variants[0].get(0).variant); // codon[1] variant
-    assertEquals(1, pep1Variants[1].size());
-    assertEquals("T", pep1Variants[1].get(0).base); // codon[2] base
-    assertNull(pep1Variants[1].get(0).variant); // no variant here
-    assertEquals(1, pep1Variants[2].size());
-    assertEquals("G", pep1Variants[2].get(0).base); // codon[3] base
-    assertNull(pep1Variants[2].get(0).variant); // no variant here
-
-    /*
-     * protein residue 2: variants on codon (AAA) bases 2 and 3
-     */
-    List<DnaVariant>[] pep2Variants = variantsMap.get(2);
-    assertEquals(3, pep2Variants.length);
-    assertEquals(1, pep2Variants[0].size());
-    // codon[1] base recorded while processing variant on codon[2]
-    assertEquals("A", pep2Variants[0].get(0).base);
-    assertNull(pep2Variants[0].get(0).variant); // no variant here
-    // codon[2] base and variant:
-    assertEquals(1, pep2Variants[1].size());
-    assertEquals("A", pep2Variants[1].get(0).base);
-    assertSame(sf2, pep2Variants[1].get(0).variant);
-    // codon[3] base was recorded when processing codon[2] variant
-    // and then the variant for codon[3] added to it
-    assertEquals(1, pep2Variants[2].size());
-    assertEquals("A", pep2Variants[2].get(0).base);
-    assertSame(sf3, pep2Variants[2].get(0).variant);
-
-    /*
-     * protein residue 3: variants on codon (TTT) base 2 only
-     */
-    List<DnaVariant>[] pep3Variants = variantsMap.get(3);
-    assertEquals(3, pep3Variants.length);
-    assertEquals(1, pep3Variants[0].size());
-    assertEquals("T", pep3Variants[0].get(0).base); // codon[1] base
-    assertNull(pep3Variants[0].get(0).variant); // no variant here
-    assertEquals(1, pep3Variants[1].size());
-    assertEquals("T", pep3Variants[1].get(0).base); // codon[2] base
-    assertSame(sf4, pep3Variants[1].get(0).variant); // codon[2] variant
-    assertEquals(1, pep3Variants[2].size());
-    assertEquals("T", pep3Variants[2].get(0).base); // codon[3] base
-    assertNull(pep3Variants[2].get(0).variant); // no variant here
-
-    /*
-     * three variants on protein position 5
-     */
-    List<DnaVariant>[] pep5Variants = variantsMap.get(5);
-    assertEquals(3, pep5Variants.length);
-    assertEquals(1, pep5Variants[0].size());
-    assertEquals("C", pep5Variants[0].get(0).base); // codon[1] base
-    assertSame(sf5, pep5Variants[0].get(0).variant); // codon[1] variant
-    assertEquals(1, pep5Variants[1].size());
-    assertEquals("C", pep5Variants[1].get(0).base); // codon[2] base
-    assertSame(sf6, pep5Variants[1].get(0).variant); // codon[2] variant
-    assertEquals(1, pep5Variants[2].size());
-    assertEquals("C", pep5Variants[2].get(0).base); // codon[3] base
-    assertSame(sf7, pep5Variants[2].get(0).variant); // codon[3] variant
-  }
-
-  /**
-   * Tests for the method that computes all peptide variants given codon
-   * variants
-   */
-  @Test(groups = "Functional")
-  public void testComputePeptideVariants()
-  {
-    /*
-     * scenario: AAATTTCCC codes for KFP
-     * variants:
-     *           GAA -> E             source: Ensembl
-     *           CAA -> Q             source: dbSNP
-     *           AAG synonymous       source: COSMIC
-     *           AAT -> N             source: Ensembl
-     *           ...TTC synonymous    source: dbSNP
-     *           ......CAC,CGC -> H,R source: COSMIC
-     *                 (one variant with two alleles)
-     */
-    SequenceI peptide = new Sequence("pep/10-12", "KFP");
-
-    /*
-     * two distinct variants for codon 1 position 1
-     * second one has clinical significance
-     */
-    String ensembl = "Ensembl";
-    String dbSnp = "dbSNP";
-    String cosmic = "COSMIC";
-    SequenceFeature sf1 = new SequenceFeature("sequence_variant", "", 1, 1,
-            0f, ensembl);
-    sf1.setValue("alleles", "A,G"); // GAA -> E
-    sf1.setValue("ID", "var1.125A>G");
-    SequenceFeature sf2 = new SequenceFeature("sequence_variant", "", 1, 1,
-            0f, dbSnp);
-    sf2.setValue("alleles", "A,C"); // CAA -> Q
-    sf2.setValue("ID", "var2");
-    sf2.setValue("clinical_significance", "Dodgy");
-    SequenceFeature sf3 = new SequenceFeature("sequence_variant", "", 3, 3,
-            0f, cosmic);
-    sf3.setValue("alleles", "A,G"); // synonymous
-    sf3.setValue("ID", "var3");
-    sf3.setValue("clinical_significance", "None");
-    SequenceFeature sf4 = new SequenceFeature("sequence_variant", "", 3, 3,
-            0f, ensembl);
-    sf4.setValue("alleles", "A,T"); // AAT -> N
-    sf4.setValue("ID", "sequence_variant:var4"); // prefix gets stripped off
-    sf4.setValue("clinical_significance", "Benign");
-    SequenceFeature sf5 = new SequenceFeature("sequence_variant", "", 6, 6,
-            0f, dbSnp);
-    sf5.setValue("alleles", "T,C"); // synonymous
-    sf5.setValue("ID", "var5");
-    sf5.setValue("clinical_significance", "Bad");
-    SequenceFeature sf6 = new SequenceFeature("sequence_variant", "", 8, 8,
-            0f, cosmic);
-    sf6.setValue("alleles", "C,A,G"); // CAC,CGC -> H,R
-    sf6.setValue("ID", "var6");
-    sf6.setValue("clinical_significance", "Good");
-
-    List<DnaVariant> codon1Variants = new ArrayList<DnaVariant>();
-    List<DnaVariant> codon2Variants = new ArrayList<DnaVariant>();
-    List<DnaVariant> codon3Variants = new ArrayList<DnaVariant>();
-    List<DnaVariant> codonVariants[] = new ArrayList[3];
-    codonVariants[0] = codon1Variants;
-    codonVariants[1] = codon2Variants;
-    codonVariants[2] = codon3Variants;
-
-    /*
-     * compute variants for protein position 1
-     */
-    codon1Variants.add(new DnaVariant("A", sf1));
-    codon1Variants.add(new DnaVariant("A", sf2));
-    codon2Variants.add(new DnaVariant("A"));
-    codon2Variants.add(new DnaVariant("A"));
-    codon3Variants.add(new DnaVariant("A", sf3));
-    codon3Variants.add(new DnaVariant("A", sf4));
-    AlignmentUtils.computePeptideVariants(peptide, 1, codonVariants);
-
-    /*
-     * compute variants for protein position 2
-     */
-    codon1Variants.clear();
-    codon2Variants.clear();
-    codon3Variants.clear();
-    codon1Variants.add(new DnaVariant("T"));
-    codon2Variants.add(new DnaVariant("T"));
-    codon3Variants.add(new DnaVariant("T", sf5));
-    AlignmentUtils.computePeptideVariants(peptide, 2, codonVariants);
-
-    /*
-     * compute variants for protein position 3
-     */
-    codon1Variants.clear();
-    codon2Variants.clear();
-    codon3Variants.clear();
-    codon1Variants.add(new DnaVariant("C"));
-    codon2Variants.add(new DnaVariant("C", sf6));
-    codon3Variants.add(new DnaVariant("C"));
-    AlignmentUtils.computePeptideVariants(peptide, 3, codonVariants);
-
-    /*
-     * verify added sequence features for
-     * var1 K -> E Ensembl
-     * var2 K -> Q dbSNP
-     * var4 K -> N Ensembl
-     * var6 P -> H COSMIC
-     * var6 P -> R COSMIC
-     */
-    SequenceFeature[] sfs = peptide.getSequenceFeatures();
-    assertEquals(5, sfs.length);
-
-    SequenceFeature sf = sfs[0];
-    assertEquals(1, sf.getBegin());
-    assertEquals(1, sf.getEnd());
-    assertEquals("p.Lys1Glu", sf.getDescription());
-    assertEquals("var1.125A>G", sf.getValue("ID"));
-    assertNull(sf.getValue("clinical_significance"));
-    assertEquals("ID=var1.125A>G", sf.getAttributes());
-    assertEquals(1, sf.links.size());
-    // link to variation is urlencoded
-    assertEquals(
-            "p.Lys1Glu var1.125A>G|http://www.ensembl.org/Homo_sapiens/Variation/Summary?v=var1.125A%3EG",
-            sf.links.get(0));
-    assertEquals(ensembl, sf.getFeatureGroup());
-
-    sf = sfs[1];
-    assertEquals(1, sf.getBegin());
-    assertEquals(1, sf.getEnd());
-    assertEquals("p.Lys1Gln", sf.getDescription());
-    assertEquals("var2", sf.getValue("ID"));
-    assertEquals("Dodgy", sf.getValue("clinical_significance"));
-    assertEquals("ID=var2;clinical_significance=Dodgy", sf.getAttributes());
-    assertEquals(1, sf.links.size());
-    assertEquals(
-            "p.Lys1Gln var2|http://www.ensembl.org/Homo_sapiens/Variation/Summary?v=var2",
-            sf.links.get(0));
-    assertEquals(dbSnp, sf.getFeatureGroup());
-
-    sf = sfs[2];
-    assertEquals(1, sf.getBegin());
-    assertEquals(1, sf.getEnd());
-    assertEquals("p.Lys1Asn", sf.getDescription());
-    assertEquals("var4", sf.getValue("ID"));
-    assertEquals("Benign", sf.getValue("clinical_significance"));
-    assertEquals("ID=var4;clinical_significance=Benign", sf.getAttributes());
-    assertEquals(1, sf.links.size());
-    assertEquals(
-            "p.Lys1Asn var4|http://www.ensembl.org/Homo_sapiens/Variation/Summary?v=var4",
-            sf.links.get(0));
-    assertEquals(ensembl, sf.getFeatureGroup());
-
-    // var5 generates two distinct protein variant features
-    sf = sfs[3];
-    assertEquals(3, sf.getBegin());
-    assertEquals(3, sf.getEnd());
-    assertEquals("p.Pro3His", sf.getDescription());
-    assertEquals("var6", sf.getValue("ID"));
-    assertEquals("Good", sf.getValue("clinical_significance"));
-    assertEquals("ID=var6;clinical_significance=Good", sf.getAttributes());
-    assertEquals(1, sf.links.size());
-    assertEquals(
-            "p.Pro3His var6|http://www.ensembl.org/Homo_sapiens/Variation/Summary?v=var6",
-            sf.links.get(0));
-    assertEquals(cosmic, sf.getFeatureGroup());
-
-    sf = sfs[4];
-    assertEquals(3, sf.getBegin());
-    assertEquals(3, sf.getEnd());
-    assertEquals("p.Pro3Arg", sf.getDescription());
-    assertEquals("var6", sf.getValue("ID"));
-    assertEquals("Good", sf.getValue("clinical_significance"));
-    assertEquals("ID=var6;clinical_significance=Good", sf.getAttributes());
-    assertEquals(1, sf.links.size());
-    assertEquals(
-            "p.Pro3Arg var6|http://www.ensembl.org/Homo_sapiens/Variation/Summary?v=var6",
-            sf.links.get(0));
-    assertEquals(cosmic, sf.getFeatureGroup());
-  }
-
-  /**
    * Tests for the method that maps the subset of a dna sequence that has CDS
    * (or subtype) feature, with CDS strand = '-' (reverse)
    */
@@ -2251,7 +2028,7 @@ public class AlignmentUtilsTests
     seq1.createDatasetSequence();
     Mapping mapping = new Mapping(seq1, new MapList(
             new int[] { 3, 6, 9, 10 }, new int[] { 1, 6 }, 1, 1));
-    Map<Integer, Map<SequenceI, Character>> map = new TreeMap<Integer, Map<SequenceI, Character>>();
+    Map<Integer, Map<SequenceI, Character>> map = new TreeMap<>();
     AlignmentUtils.addMappedPositions(seq1, from, mapping, map);
 
     /*
@@ -2283,7 +2060,7 @@ public class AlignmentUtilsTests
     seq1.createDatasetSequence();
     Mapping mapping = new Mapping(seq1, new MapList(
             new int[] { 3, 6, 9, 10 }, new int[] { 1, 6 }, 1, 1));
-    Map<Integer, Map<SequenceI, Character>> map = new TreeMap<Integer, Map<SequenceI, Character>>();
+    Map<Integer, Map<SequenceI, Character>> map = new TreeMap<>();
     AlignmentUtils.addMappedPositions(seq1, from, mapping, map);
 
     /*
@@ -2455,9 +2232,16 @@ public class AlignmentUtilsTests
     AlignmentI al2 = new Alignment(new SequenceI[] { dna3, dna4 });
     ((Alignment) al2).createDatasetAlignment();
 
+    /*
+     * alignment removes gapped columns (two internal, two trailing)
+     */
     assertTrue(AlignmentUtils.alignAsSameSequences(al1, al2));
-    assertEquals(seq1, al1.getSequenceAt(0).getSequenceAsString());
-    assertEquals(seq2, al1.getSequenceAt(1).getSequenceAsString());
+    String aligned1 = "-cc-GG-GTTT-aaa";
+    assertEquals(aligned1,
+            al1.getSequenceAt(0).getSequenceAsString());
+    String aligned2 = "C--C-Cgg-gtttAAA";
+    assertEquals(aligned2,
+            al1.getSequenceAt(1).getSequenceAsString());
 
     /*
      * add another sequence to 'aligned' - should still succeed, since
@@ -2467,8 +2251,8 @@ public class AlignmentUtilsTests
     dna5.createDatasetSequence();
     al2.addSequence(dna5);
     assertTrue(AlignmentUtils.alignAsSameSequences(al1, al2));
-    assertEquals(seq1, al1.getSequenceAt(0).getSequenceAsString());
-    assertEquals(seq2, al1.getSequenceAt(1).getSequenceAsString());
+    assertEquals(aligned1, al1.getSequenceAt(0).getSequenceAsString());
+    assertEquals(aligned2, al1.getSequenceAt(1).getSequenceAsString());
 
     /*
      * add another sequence to 'unaligned' - should fail, since now not
@@ -2486,15 +2270,15 @@ public class AlignmentUtilsTests
   {
     SequenceI dna1 = new Sequence("dna1", "cccGGGTTTaaa");
     SequenceI dna2 = new Sequence("dna2", "CCCgggtttAAA");
-    SequenceI as1 = dna1.deriveSequence();
-    SequenceI as2 = dna1.deriveSequence().getSubSequence(3, 7);
-    SequenceI as3 = dna2.deriveSequence();
+    SequenceI as1 = dna1.deriveSequence(); // cccGGGTTTaaa/1-12
+    SequenceI as2 = dna1.deriveSequence().getSubSequence(3, 7); // GGGT/4-7
+    SequenceI as3 = dna2.deriveSequence(); // CCCgggtttAAA/1-12
     as1.insertCharAt(6, 5, '-');
-    String s_as1 = as1.getSequenceAsString();
+    assertEquals("cccGGG-----TTTaaa", as1.getSequenceAsString());
     as2.insertCharAt(6, 5, '-');
-    String s_as2 = as2.getSequenceAsString();
-    as3.insertCharAt(6, 5, '-');
-    String s_as3 = as3.getSequenceAsString();
+    assertEquals("GGGT-----", as2.getSequenceAsString());
+    as3.insertCharAt(3, 5, '-');
+    assertEquals("CCC-----gggtttAAA", as3.getSequenceAsString());
     AlignmentI aligned = new Alignment(new SequenceI[] { as1, as2, as3 });
 
     // why do we need to cast this still ?
@@ -2506,10 +2290,316 @@ public class AlignmentUtilsTests
         uas3 });
     ((Alignment) tobealigned).createDatasetAlignment();
 
+    /*
+     * alignAs lines up dataset sequences and removes empty columns (two)
+     */
     assertTrue(AlignmentUtils.alignAsSameSequences(tobealigned, aligned));
-    assertEquals(s_as1, uas1.getSequenceAsString());
-    assertEquals(s_as2, uas2.getSequenceAsString());
-    assertEquals(s_as3, uas3.getSequenceAsString());
+    assertEquals("cccGGG---TTTaaa", uas1.getSequenceAsString());
+    assertEquals("GGGT", uas2.getSequenceAsString());
+    assertEquals("CCC---gggtttAAA", uas3.getSequenceAsString());
+  }
+
+  @Test(groups = { "Functional" })
+  public void testTransferGeneLoci()
+  {
+    SequenceI from = new Sequence("transcript",
+            "aaacccgggTTTAAACCCGGGtttaaacccgggttt");
+    SequenceI to = new Sequence("CDS", "TTTAAACCCGGG");
+    MapList map = new MapList(new int[] { 1, 12 }, new int[] { 10, 21 }, 1,
+            1);
+
+    /*
+     * first with nothing to transfer
+     */
+    AlignmentUtils.transferGeneLoci(from, map, to);
+    assertNull(to.getGeneLoci());
+
+    /*
+     * next with gene loci set on 'from' sequence
+     */
+    int[] exons = new int[] { 100, 105, 155, 164, 210, 229 };
+    MapList geneMap = new MapList(new int[] { 1, 36 }, exons, 1, 1);
+    from.setGeneLoci("human", "GRCh38", "7", geneMap);
+    AlignmentUtils.transferGeneLoci(from, map, to);
+
+    GeneLociI toLoci = to.getGeneLoci();
+    assertNotNull(toLoci);
+    // DBRefEntry constructor upper-cases 'source'
+    assertEquals("HUMAN", toLoci.getSpeciesId());
+    assertEquals("GRCh38", toLoci.getAssemblyId());
+    assertEquals("7", toLoci.getChromosomeId());
+
+    /*
+     * transcript 'exons' are 1-6, 7-16, 17-36
+     * CDS 1:12 is transcript 10-21
+     * transcript 'CDS' is 10-16, 17-21
+     * which is 'gene' 158-164, 210-214
+     */
+    MapList toMap = toLoci.getMapping();
+    assertEquals(1, toMap.getFromRanges().size());
+    assertEquals(2, toMap.getFromRanges().get(0).length);
+    assertEquals(1, toMap.getFromRanges().get(0)[0]);
+    assertEquals(12, toMap.getFromRanges().get(0)[1]);
+    assertEquals(2, toMap.getToRanges().size());
+    assertEquals(2, toMap.getToRanges().get(0).length);
+    assertEquals(158, toMap.getToRanges().get(0)[0]);
+    assertEquals(164, toMap.getToRanges().get(0)[1]);
+    assertEquals(210, toMap.getToRanges().get(1)[0]);
+    assertEquals(214, toMap.getToRanges().get(1)[1]);
+    // or summarised as (but toString might change in future):
+    assertEquals("[ [1, 12] ] 1:1 to [ [158, 164] [210, 214] ]",
+            toMap.toString());
+
+    /*
+     * an existing value is not overridden 
+     */
+    geneMap = new MapList(new int[] { 1, 36 }, new int[] { 36, 1 }, 1, 1);
+    from.setGeneLoci("inhuman", "GRCh37", "6", geneMap);
+    AlignmentUtils.transferGeneLoci(from, map, to);
+    assertEquals("GRCh38", toLoci.getAssemblyId());
+    assertEquals("7", toLoci.getChromosomeId());
+    toMap = toLoci.getMapping();
+    assertEquals("[ [1, 12] ] 1:1 to [ [158, 164] [210, 214] ]",
+            toMap.toString());
+  }
+
+  /**
+   * Tests for the method that maps nucleotide to protein based on CDS features
+   */
+  @Test(groups = "Functional")
+  public void testMapCdsToProtein()
+  {
+    SequenceI peptide = new Sequence("pep", "KLQ");
+
+    /*
+     * Case 1: CDS 3 times length of peptide
+     * NB method only checks lengths match, not translation
+     */
+    SequenceI dna = new Sequence("dna", "AACGacgtCTCCT");
+    dna.createDatasetSequence();
+    dna.addSequenceFeature(new SequenceFeature("CDS", "", 1, 4, null));
+    dna.addSequenceFeature(new SequenceFeature("CDS", "", 9, 13, null));
+    MapList ml = AlignmentUtils.mapCdsToProtein(dna, peptide);
+    assertEquals(3, ml.getFromRatio());
+    assertEquals(1, ml.getToRatio());
+    assertEquals("[[1, 3]]",
+            Arrays.deepToString(ml.getToRanges().toArray()));
+    assertEquals("[[1, 4], [9, 13]]",
+            Arrays.deepToString(ml.getFromRanges().toArray()));
+
+    /*
+     * Case 2: CDS 3 times length of peptide + stop codon
+     * (note code does not currently check trailing codon is a stop codon)
+     */
+    dna = new Sequence("dna", "AACGacgtCTCCTCCC");
+    dna.createDatasetSequence();
+    dna.addSequenceFeature(new SequenceFeature("CDS", "", 1, 4, null));
+    dna.addSequenceFeature(new SequenceFeature("CDS", "", 9, 16, null));
+    ml = AlignmentUtils.mapCdsToProtein(dna, peptide);
+    assertEquals(3, ml.getFromRatio());
+    assertEquals(1, ml.getToRatio());
+    assertEquals("[[1, 3]]",
+            Arrays.deepToString(ml.getToRanges().toArray()));
+    assertEquals("[[1, 4], [9, 13]]",
+            Arrays.deepToString(ml.getFromRanges().toArray()));
+
+    /*
+     * Case 3: CDS longer than 3 * peptide + stop codon - no mapping is made
+     */
+    dna = new Sequence("dna", "AACGacgtCTCCTTGATCA");
+    dna.createDatasetSequence();
+    dna.addSequenceFeature(new SequenceFeature("CDS", "", 1, 4, null));
+    dna.addSequenceFeature(new SequenceFeature("CDS", "", 9, 19, null));
+    ml = AlignmentUtils.mapCdsToProtein(dna, peptide);
+    assertNull(ml);
+
+    /*
+     * Case 4: CDS shorter than 3 * peptide - no mapping is made
+     */
+    dna = new Sequence("dna", "AACGacgtCTCC");
+    dna.createDatasetSequence();
+    dna.addSequenceFeature(new SequenceFeature("CDS", "", 1, 4, null));
+    dna.addSequenceFeature(new SequenceFeature("CDS", "", 9, 12, null));
+    ml = AlignmentUtils.mapCdsToProtein(dna, peptide);
+    assertNull(ml);
+
+    /*
+     * Case 5: CDS 3 times length of peptide + part codon - mapping is truncated
+     */
+    dna = new Sequence("dna", "AACGacgtCTCCTTG");
+    dna.createDatasetSequence();
+    dna.addSequenceFeature(new SequenceFeature("CDS", "", 1, 4, null));
+    dna.addSequenceFeature(new SequenceFeature("CDS", "", 9, 15, null));
+    ml = AlignmentUtils.mapCdsToProtein(dna, peptide);
+    assertEquals(3, ml.getFromRatio());
+    assertEquals(1, ml.getToRatio());
+    assertEquals("[[1, 3]]",
+            Arrays.deepToString(ml.getToRanges().toArray()));
+    assertEquals("[[1, 4], [9, 13]]",
+            Arrays.deepToString(ml.getFromRanges().toArray()));
+
+    /*
+     * Case 6: incomplete start codon corresponding to X in peptide
+     */
+    dna = new Sequence("dna", "ACGacgtCTCCTTGG");
+    dna.createDatasetSequence();
+    SequenceFeature sf = new SequenceFeature("CDS", "", 1, 3, null);
+    sf.setPhase("2"); // skip 2 positions (AC) to start of next codon (GCT)
+    dna.addSequenceFeature(sf);
+    dna.addSequenceFeature(new SequenceFeature("CDS", "", 8, 15, null));
+    peptide = new Sequence("pep", "XLQ");
+    ml = AlignmentUtils.mapCdsToProtein(dna, peptide);
+    assertEquals("[[2, 3]]",
+            Arrays.deepToString(ml.getToRanges().toArray()));
+    assertEquals("[[3, 3], [8, 12]]",
+            Arrays.deepToString(ml.getFromRanges().toArray()));
   }
 
+  /**
+   * Tests for the method that locates the CDS sequence that has a mapping to
+   * the given protein. That is, given a transcript-to-peptide mapping, find the
+   * cds-to-peptide mapping that relates to both, and return the CDS sequence.
+   */
+  @Test
+  public void testFindCdsForProtein()
+  {
+    List<AlignedCodonFrame> mappings = new ArrayList<>();
+    AlignedCodonFrame acf1 = new AlignedCodonFrame();
+    mappings.add(acf1);
+
+    SequenceI dna1 = new Sequence("dna1", "cgatATcgGCTATCTATGacg");
+    dna1.createDatasetSequence();
+
+    // NB we currently exclude STOP codon from CDS sequences
+    // the test would need to change if this changes in future
+    SequenceI cds1 = new Sequence("cds1", "ATGCTATCT");
+    cds1.createDatasetSequence();
+
+    SequenceI pep1 = new Sequence("pep1", "MLS");
+    pep1.createDatasetSequence();
+    List<AlignedCodonFrame> seqMappings = new ArrayList<>();
+    MapList mapList = new MapList(
+            new int[]
+            { 5, 6, 9, 15 }, new int[] { 1, 3 }, 3, 1);
+    Mapping dnaToPeptide = new Mapping(pep1.getDatasetSequence(), mapList);
+    
+    // add dna to peptide mapping
+    seqMappings.add(acf1);
+    acf1.addMap(dna1.getDatasetSequence(), pep1.getDatasetSequence(),
+            mapList);
+
+    /*
+     * first case - no dna-to-CDS mapping exists - search fails
+     */
+    SequenceI seq = AlignmentUtils.findCdsForProtein(mappings, dna1,
+            seqMappings, dnaToPeptide);
+    assertNull(seq);
+
+    /*
+     * second case - CDS-to-peptide mapping exists but no dna-to-CDS
+     * - search fails
+     */
+    // todo this test fails if the mapping is added to acf1, not acf2
+    // need to tidy up use of lists of mappings in AlignedCodonFrame
+    AlignedCodonFrame acf2 = new AlignedCodonFrame();
+    mappings.add(acf2);
+    MapList cdsToPeptideMapping = new MapList(new int[]
+    { 1, 9 }, new int[] { 1, 3 }, 3, 1);
+    acf2.addMap(cds1.getDatasetSequence(), pep1.getDatasetSequence(),
+            cdsToPeptideMapping);
+    assertNull(AlignmentUtils.findCdsForProtein(mappings, dna1, seqMappings,
+            dnaToPeptide));
+
+    /*
+     * third case - add dna-to-CDS mapping - CDS is now found!
+     */
+    MapList dnaToCdsMapping = new MapList(new int[] { 5, 6, 9, 15 },
+            new int[]
+            { 1, 9 }, 1, 1);
+    acf1.addMap(dna1.getDatasetSequence(), cds1.getDatasetSequence(),
+            dnaToCdsMapping);
+    seq = AlignmentUtils.findCdsForProtein(mappings, dna1, seqMappings,
+            dnaToPeptide);
+    assertSame(seq, cds1.getDatasetSequence());
+  }
+
+  /**
+   * Tests for the method that locates the CDS sequence that has a mapping to
+   * the given protein. That is, given a transcript-to-peptide mapping, find the
+   * cds-to-peptide mapping that relates to both, and return the CDS sequence.
+   * This test is for the case where transcript and CDS are the same length.
+   */
+  @Test
+  public void testFindCdsForProtein_noUTR()
+  {
+    List<AlignedCodonFrame> mappings = new ArrayList<>();
+    AlignedCodonFrame acf1 = new AlignedCodonFrame();
+    mappings.add(acf1);
+  
+    SequenceI dna1 = new Sequence("dna1", "ATGCTATCTTAA");
+    dna1.createDatasetSequence();
+  
+    // NB we currently exclude STOP codon from CDS sequences
+    // the test would need to change if this changes in future
+    SequenceI cds1 = new Sequence("cds1", "ATGCTATCT");
+    cds1.createDatasetSequence();
+  
+    SequenceI pep1 = new Sequence("pep1", "MLS");
+    pep1.createDatasetSequence();
+    List<AlignedCodonFrame> seqMappings = new ArrayList<>();
+    MapList mapList = new MapList(
+            new int[]
+            { 1, 9 }, new int[] { 1, 3 }, 3, 1);
+    Mapping dnaToPeptide = new Mapping(pep1.getDatasetSequence(), mapList);
+    
+    // add dna to peptide mapping
+    seqMappings.add(acf1);
+    acf1.addMap(dna1.getDatasetSequence(), pep1.getDatasetSequence(),
+            mapList);
+  
+    /*
+     * first case - transcript lacks CDS features - it appears to be
+     * the CDS sequence and is returned
+     */
+    SequenceI seq = AlignmentUtils.findCdsForProtein(mappings, dna1,
+            seqMappings, dnaToPeptide);
+    assertSame(seq, dna1.getDatasetSequence());
+  
+    /*
+     * second case - transcript has CDS feature - this means it is
+     * not returned as a match for CDS (CDS sequences don't have CDS features)
+     */
+    dna1.addSequenceFeature(
+            new SequenceFeature(SequenceOntologyI.CDS, "cds", 1, 12, null));
+    seq = AlignmentUtils.findCdsForProtein(mappings, dna1, seqMappings,
+            dnaToPeptide);
+    assertNull(seq);
+
+    /*
+     * third case - CDS-to-peptide mapping exists but no dna-to-CDS
+     * - search fails
+     */
+    // todo this test fails if the mapping is added to acf1, not acf2
+    // need to tidy up use of lists of mappings in AlignedCodonFrame
+    AlignedCodonFrame acf2 = new AlignedCodonFrame();
+    mappings.add(acf2);
+    MapList cdsToPeptideMapping = new MapList(new int[]
+    { 1, 9 }, new int[] { 1, 3 }, 3, 1);
+    acf2.addMap(cds1.getDatasetSequence(), pep1.getDatasetSequence(),
+            cdsToPeptideMapping);
+    assertNull(AlignmentUtils.findCdsForProtein(mappings, dna1, seqMappings,
+            dnaToPeptide));
+  
+    /*
+     * fourth case - add dna-to-CDS mapping - CDS is now found!
+     */
+    MapList dnaToCdsMapping = new MapList(new int[] { 1, 9 },
+            new int[]
+            { 1, 9 }, 1, 1);
+    acf1.addMap(dna1.getDatasetSequence(), cds1.getDatasetSequence(),
+            dnaToCdsMapping);
+    seq = AlignmentUtils.findCdsForProtein(mappings, dna1, seqMappings,
+            dnaToPeptide);
+    assertSame(seq, cds1.getDatasetSequence());
+  }
 }