Retrieve full name matches over hazy short hash matches

src/main/java/jenkins/plugins/git/AbstractGitSCMSource.java

@@ -870,6 +870,7 @@
         Set<String> fullHashMatches = new TreeSet<>();
         String fullHashMatch = null;
         GitRefSCMRevision candidateOtherRef = null;
+        Boolean shortRevisionAmbiguity = false;
         for (Map.Entry<String,ObjectId> entry: remoteReferences.entrySet()) {
             String name = entry.getKey();
             String rev = entry.getValue().name();
@@ -923,18 +924,25 @@
                     break;
                 }
             }
-            if (rev.toLowerCase(Locale.ENGLISH).startsWith(revision.toLowerCase(Locale.ENGLISH))) {
+            if (!revision.isEmpty() && rev.toLowerCase(Locale.ENGLISH).startsWith(revision.toLowerCase(Locale.ENGLISH))) {
                 shortNameMatches.add(name);
+                listener.getLogger().printf("Candidate partial match: %s revision %s%n", name, rev);
                 if (shortHashMatch == null) {
-                    listener.getLogger().printf("Candidate partial match: %s revision %s%n", name, rev);
                     shortHashMatch = rev;
                 } else {
-                    listener.getLogger().printf("Candidate partial match: %s revision %s%n", name, rev);
                     listener.getLogger().printf("Cannot resolve ambiguous short revision %s%n", revision);
-                    return null;
+                    if (fullTagMatches.isEmpty() && fullHashMatches.isEmpty() && fullHashMatch == null && candidateOtherRef == null) {
+                        // We haven't found any matches, and we have ambiguous matches, cannot determine
+                        shortRevisionAmbiguity = true;
+                    }
                 }
             }
         }
+        if (fullHashMatch != null) {
+            // JENKINS-62592, for predictability, if an exact match is found, that should be returned
+            //since this would have been skipped if this was a head or a tag we can just return whatever
+            return new GitRefSCMRevision(new GitRefSCMHead(fullHashMatch, fullHashMatches.iterator().next()), fullHashMatch);
+        }
         if (!fullTagMatches.isEmpty()) {
             // we just want a tag so we can do a minimal fetch
             String name = StringUtils.removeStart(fullTagMatches.iterator().next(), Constants.R_TAGS);
@@ -944,34 +952,6 @@
             context.wantTags(true);
             context.withoutRefSpecs();
         }
-        if (fullHashMatch != null) {
-            //since this would have been skipped if this was a head or a tag we can just return whatever
-            return new GitRefSCMRevision(new GitRefSCMHead(fullHashMatch, fullHashMatches.iterator().next()), fullHashMatch);
-        }
-        if (shortHashMatch != null) {
-            // woot this seems unambiguous
-            for (String name: shortNameMatches) {
-                if (name.startsWith(Constants.R_HEADS)) {
-                    listener.getLogger().printf("Selected match: %s revision %s%n", name, shortHashMatch);
-                    // WIN it's also a branch
-                    return new GitBranchSCMRevision(new GitBranchSCMHead(StringUtils.removeStart(name, Constants.R_HEADS)),
-                            shortHashMatch);
-                } else if (name.startsWith(Constants.R_TAGS)) {
-                    tagName = StringUtils.removeStart(name, Constants.R_TAGS);
-                    context.wantBranches(false);
-                    context.wantTags(true);
-                    context.withoutRefSpecs();
-                }
-            }
-            if (tagName != null) {
-                listener.getLogger().printf("Selected match: %s revision %s%n", tagName, shortHashMatch);
-            } else {
-                return new GitRefSCMRevision(new GitRefSCMHead(shortHashMatch, shortNameMatches.iterator().next()), shortHashMatch);
-            }
-        }
-        if (candidateOtherRef != null) {
-            return candidateOtherRef;
-        }
         //if PruneStaleBranches it should take affect on the following retrievals
         boolean pruneRefs = context.pruneRefs();
         if (tagName != null) {
@@ -998,6 +978,34 @@
                     context,
                     listener, pruneRefs, retrieveContext);
         }
+        if (shortHashMatch != null) {
+            // woot this seems unambiguous
+            for (String name: shortNameMatches) {
+                if (name.startsWith(Constants.R_HEADS)) {
+                    listener.getLogger().printf("Selected match: %s revision %s%n", name, shortHashMatch);
+                    // WIN it's also a branch
+                    return new GitBranchSCMRevision(new GitBranchSCMHead(StringUtils.removeStart(name, Constants.R_HEADS)),
+                            shortHashMatch);
+                } else if (name.startsWith(Constants.R_TAGS)) {
+                    tagName = StringUtils.removeStart(name, Constants.R_TAGS);
+                    context.wantBranches(false);
+                    context.wantTags(true);
+                    context.withoutRefSpecs();
+                }
+            }
+            if (tagName != null) {
+                listener.getLogger().printf("Selected match: %s revision %s%n", tagName, shortHashMatch);
+            } else {
+                return new GitRefSCMRevision(new GitRefSCMHead(shortHashMatch, shortNameMatches.iterator().next()), shortHashMatch);
+            }
+        }
+        if (candidateOtherRef != null) {
+            return candidateOtherRef;
+        }
+        if (shortRevisionAmbiguity) {
+            // Check if we have any other matches first, if not, return null as we cannot determine a match
+            return null;
+        }
         // Pokémon!... Got to catch them all
         listener.getLogger().printf("Could not find %s in remote references. "
                         + "Pulling heads to local for deep search...%n", revision);
@@ -1015,7 +1023,6 @@
                                           //just to be safe
                                           listener.error("Could not resolve %s", revision);
                                           return null;
-
                                       }
                                       hash = objectId.name();
                                       String candidatePrefix = Constants.R_REMOTES.substring(Constants.R_REFS.length())

src/test/java/jenkins/plugins/git/AbstractGitSCMSourceTest.java

@@ -8,6 +8,7 @@
 import com.cloudbees.plugins.credentials.common.StandardCredentials;
 import com.cloudbees.plugins.credentials.domains.Domain;
 import com.cloudbees.plugins.credentials.impl.UsernamePasswordCredentialsImpl;
+import edu.umd.cs.findbugs.annotations.NonNull;
 import hudson.EnvVars;
 import hudson.FilePath;
 import hudson.Launcher;
@@ -25,6 +26,7 @@
 import hudson.plugins.git.extensions.impl.LocalBranch;
 import hudson.util.StreamTaskListener;
 import java.io.File;
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -38,7 +40,6 @@
 import jenkins.plugins.git.traits.IgnoreOnPushNotificationTrait;
 import jenkins.plugins.git.traits.PruneStaleBranchTrait;
 import jenkins.plugins.git.traits.TagDiscoveryTrait;
-
 import jenkins.scm.api.SCMHead;
 import jenkins.scm.api.SCMHeadObserver;
 import jenkins.scm.api.SCMRevision;
@@ -53,6 +54,7 @@
 import jenkins.scm.api.SCMSourceCriteria;
 import jenkins.scm.api.SCMSourceOwner;
 import jenkins.scm.api.metadata.PrimaryInstanceMetadataAction;
+import jenkins.scm.api.trait.SCMSourceTrait;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.transport.RefSpec;
@@ -425,7 +427,7 @@ public void retrieveByName() throws Exception {
         listener.getLogger().printf("%n=== fetch('%s') ===%n%n", devHash);
         rev = source.fetch(devHash, listener, null);
         assertThat(rev, instanceOf(AbstractGitSCMSource.SCMRevisionImpl.class));
-        assertThat(((AbstractGitSCMSource.SCMRevisionImpl) rev).getHash(), is(devHash));
+        assertThat(((AbstractGitSCMSource.SCMRevisionImpl)rev).getHash(), is(devHash));
         assertThat(rev.getHead().getName(), is("dev"));
 
         listener.getLogger().printf("%n=== fetch('%s') ===%n%n", devHash.substring(0, 10));
@@ -536,7 +538,7 @@ private void retrievePrimaryHead(boolean duplicatePrimary) throws Exception {
         }
 
         PrimaryInstanceMetadataAction primary = null;
-        for (Action a: actions) {
+        for (Action a : actions) {
             if (a instanceof PrimaryInstanceMetadataAction) {
                 primary = (PrimaryInstanceMetadataAction) a;
                 break;
@@ -835,7 +837,7 @@ public void fetchOtherRef() throws Exception {
         StreamTaskListener listener = StreamTaskListener.fromStderr();
 
         final SCMHeadObserver.Collector collector =
-        source.fetch((SCMSourceCriteria) (probe, listener1) -> true, new SCMHeadObserver.Collector(), listener);
+                source.fetch((SCMSourceCriteria) (probe, listener1) -> true, new SCMHeadObserver.Collector(), listener);
 
         final Map<SCMHead, SCMRevision> result = collector.result();
         assertThat(result.entrySet(), hasSize(4));
@@ -1157,6 +1159,115 @@ public void when_commits_added_during_discovery_we_do_not_crash() throws Excepti
             sharedSampleRepo = null;
         }
     }
+
+    @Issue("JENKINS-62592")
+    @Test
+    public void exactBranchMatchShouldSupersedePartialBranchMatch() throws Exception {
+        sampleRepo.init();
+        String masterHash = sampleRepo.head();
+        sampleRepo.git("checkout", "-b", "dev");
+        sampleRepo.write("file", "modified");
+        sampleRepo.git("commit", "--all", "--message=dev");
+        sampleRepo.git("tag", "v1");
+        String v1Hash = sampleRepo.head();
+        sampleRepo.write("file", "modified2");
+        sampleRepo.git("commit", "--all", "--message=dev2");
+        sampleRepo.git("tag", "-a", "v2", "-m", "annotated");
+        String v2Hash = sampleRepo.head();
+        sampleRepo.write("file", "modified3");
+        sampleRepo.git("commit", "--all", "--message=dev3");
+        // Grab the devHash, but lets try and generate a hash that we know will cause an issue in our test
+        ArrayList<String> hashFirstLetter = new ArrayList<>(
+                Arrays.asList(masterHash.substring(0, 1), v1Hash.substring(0, 1), v2Hash.substring(0, 1))
+        );
+        sampleRepo.git("tag", "devTag");
+        String devTagHash = sampleRepo.head();
+        int devTagIteration = 4; // In order to name new files and create new commits
+        String previousNewHash = null;
+        String newHash = devTagHash;
+        while (!hashFirstLetter.contains(devTagHash.substring(0, 1))) {
+            // Generate a new commit and try again
+            sampleRepo.git("tag", "devTag" + devTagIteration);
+            sampleRepo.write("file", "modified" + devTagIteration);
+            sampleRepo.git("commit", "--all", "--message=dev" + (devTagIteration++));
+            previousNewHash = newHash;
+            newHash = sampleRepo.head();
+            hashFirstLetter.add(newHash.substring(0, 1));
+        }
+        GitSCMSource source = new GitSCMSource(sampleRepo.toString());
+        source.setTraits(new ArrayList<>());
+
+        TaskListener listener = StreamTaskListener.fromStderr();
+        listener.getLogger().printf("ArrayList of first hash chars: %s", hashFirstLetter);
+
+        // Test existing functionality with additional revisions
+        listener.getLogger().println("\n=== fetch('master') ===\n");
+        SCMRevision rev = source.fetch("master", listener, null);
+        assertThat(rev, instanceOf(AbstractGitSCMSource.SCMRevisionImpl.class));
+        assertThat(((AbstractGitSCMSource.SCMRevisionImpl)rev).getHash(), is(masterHash));
+        listener.getLogger().println("\n=== fetch('v1') ===\n");
+        rev = source.fetch("v1", listener, null);
+        assertThat(rev, instanceOf(GitTagSCMRevision.class));
+        assertThat(((GitTagSCMRevision)rev).getHash(), is(v1Hash));
+        listener.getLogger().println("\n=== fetch('v2') ===\n");
+        rev = source.fetch("v2", listener, null);
+        assertThat(rev, instanceOf(GitTagSCMRevision.class));
+        assertThat(((GitTagSCMRevision)rev).getHash(), is(v2Hash));
+
+        listener.getLogger().printf("%n=== fetch('%s') ===%n%n", masterHash);
+        rev = source.fetch(masterHash, listener, null);
+        assertThat(rev, instanceOf(AbstractGitSCMSource.SCMRevisionImpl.class));
+        assertThat(((AbstractGitSCMSource.SCMRevisionImpl)rev).getHash(), is(masterHash));
+        assertThat(rev.getHead().getName(), is("master"));
+
+        // Test new functionality and verify that we are able to grab what we expect (full match versus hazy short hash)
+        if (!devTagHash.equals(newHash)) {
+            listener.getLogger().printf("%n=== fetch('%s') ===%n%n", newHash);
+            rev = source.fetch(newHash, listener, null);
+            assertThat(rev, instanceOf(AbstractGitSCMSource.SCMRevisionImpl.class));
+            assertThat(((AbstractGitSCMSource.SCMRevisionImpl)rev).getHash(), is(newHash));
+            assertThat(rev.getHead().getName(), is("dev"));
+
+            listener.getLogger().printf("%n=== fetch('%s') short hash ===%n%n", newHash.substring(0, 6));
+            rev = source.fetch(newHash.substring(0, 6), listener, null);
+            assertThat(rev, instanceOf(AbstractGitSCMSource.SCMRevisionImpl.class));
+            assertThat(((AbstractGitSCMSource.SCMRevisionImpl)rev).getHash(), is(newHash));
+            assertThat(rev.getHead().getName(), is("dev"));
+
+
+            int lastDevTag = devTagIteration == 4 ? 4 : devTagIteration - 1;
+            String headHash = devTagIteration == 4 ? devTagHash : previousNewHash;
+            listener.getLogger().printf("%n=== fetch(devTag%d) ===%n%n", lastDevTag);
+            rev = source.fetch("devTag" + lastDevTag, listener, null);
+            assertThat(rev, instanceOf(AbstractGitSCMSource.SCMRevisionImpl.class));
+            assertThat(rev.getHead().getName(), is("devTag" + lastDevTag));
+            assertThat(((AbstractGitSCMSource.SCMRevisionImpl)rev).getHash(), is(headHash));
+
+            String ambiguousTag = hashFirstLetter.get(hashFirstLetter.size() - 1);
+            String ambiguousHash = sampleRepo.head();
+            sampleRepo.git("tag", ambiguousTag);
+            sampleRepo.write("file", "modified and ambiguous");
+            sampleRepo.git("commit", "--all", "--message=ambiguousTagCommit");
+            listener.getLogger().printf("%n=== fetch(%s) ===%n%n", ambiguousTag);
+            rev = source.fetch(ambiguousTag, listener, null);
+            assertThat(rev, instanceOf(AbstractGitSCMSource.SCMRevisionImpl.class));
+            assertThat(rev.getHead().getName(), is(ambiguousTag));
+            assertThat(((AbstractGitSCMSource.SCMRevisionImpl)rev).getHash(), is(ambiguousHash));
+
+            // Remove ambiguous tag from the repo and thne create a branch with the ambiguous search
+            sampleRepo.git("tag", "-d", ambiguousTag);
+            sampleRepo.git("checkout", "-b", ambiguousTag);
+            sampleRepo.write("file", "modified and ambiguous but a branch this time!");
+            sampleRepo.git("commit", "--all", "--message=ambiguousBranchCommit");
+            listener.getLogger().printf("%n=== fetch(%s) branch ===%n%n", ambiguousTag);
+            String ambiguousBranchHash = sampleRepo.head();
+            rev = source.fetch(ambiguousTag, listener, null);
+            assertThat(rev, instanceOf(AbstractGitSCMSource.SCMRevisionImpl.class));
+            assertThat(rev.getHead().getName(), is(ambiguousTag));
+            assertThat(((AbstractGitSCMSource.SCMRevisionImpl)rev).getHash(), is(ambiguousBranchHash));
+        }
+    }
+
     //Ugly but MockGitClient needs to be static and no good way to pass it on
     static GitSampleRepoRule sharedSampleRepo;