Add VersionDetails#branchName for current branch of HEAD (#43)

* Add VersionDetails#branchName for current branch of HEAD

* address comments

Author: jared2501

readme.md

@@ -10,26 +10,33 @@ It behaves exactly as the JGit `git describe` method behaves, except that when t
 state, appends `.dirty` to the version string.
 
 The second, called `versionDetails()`, returns an object containing the specific details of the version string:
-the tag name, and the commit count since the tag.
+the tag name, the commit count since the tag, the current commit hash of HEAD, and an optional branch name of HEAD.
 
 Usage
 -----
 Apply the plugin using standard Gradle convention:
 
-    plugins {
-        id 'com.palantir.git-version' version '<current version>'
-    }
+```groovy
+plugins {
+    id 'com.palantir.git-version' version '<current version>'
+}
+```
 
 Set the version of a project by calling:
 
-    version gitVersion()
+```groovy
+version gitVersion()
+```
 
 You can get an object containing more detailed information by calling:
 
-    def details = versionDetails()
-    details.lastTag
-    details.commitDistance
-    details.gitHash
+```groovy
+def details = versionDetails()
+details.lastTag
+details.commitDistance
+details.gitHash
+details.branchName // is null if the repository in detached HEAD mode
+```
 
 Tasks
 -----

src/main/groovy/com/palantir/gradle/gitversion/GitVersionPlugin.groovy

@@ -15,15 +15,15 @@
  */
 package com.palantir.gradle.gitversion
 
-import groovy.transform.*
-
-import java.util.regex.Matcher
-
+import groovy.transform.Memoized
 import org.eclipse.jgit.api.Git
 import org.eclipse.jgit.internal.storage.file.FileRepository
+import org.eclipse.jgit.lib.Constants
 import org.gradle.api.Plugin
 import org.gradle.api.Project
 
+import java.util.regex.Matcher
+
 class GitVersionPlugin implements Plugin<Project> {
 
     // Gradle returns 'unspecified' when no version is set
@@ -55,10 +55,17 @@ class GitVersionPlugin implements Plugin<Project> {
     @Memoized
     private String gitHash(Project project) {
         Git git = gitRepo(project)
-        try {
-            return git.getRepository().getRef("HEAD").getObjectId().abbreviate(VERSION_ABBR_LENGTH).name()
-        } catch (Throwable t) {
-            return UNSPECIFIED_VERSION
+        return git.getRepository().getRef("HEAD").getObjectId().abbreviate(VERSION_ABBR_LENGTH).name()
+    }
+
+    @Memoized
+    private String gitBranchName(Project project) {
+        Git git = gitRepo(project)
+        def ref = git.repository.getRef(git.repository.branch)
+        if (ref == null) {
+            return null
+        } else {
+            return ref.getName().substring(Constants.R_HEADS.length())
         }
     }
 
@@ -69,22 +76,23 @@ class GitVersionPlugin implements Plugin<Project> {
 
         project.ext.versionDetails = {
             String description = gitDesc(project)
-            String hash = gitHash(project)
-
             if (description.equals(UNSPECIFIED_VERSION)) {
                 return null
             }
 
+            String hash = gitHash(project)
+            String branchName = gitBranchName(project)
+
             if (!(description =~ /.*g.?[0-9a-fA-F]{3,}/)) {
                 // Description has no git hash so it is just the tag name
-                return new VersionDetails(description, 0, hash)
+                return new VersionDetails(description, 0, hash, branchName)
             }
 
             Matcher match = (description =~ /(.*)-([0-9]+)-g.?[0-9a-fA-F]{3,}/)
             String tagName = match[0][1]
             int commitCount = Integer.valueOf(match[0][2])
 
-            return new VersionDetails(tagName, commitCount, hash)
+            return new VersionDetails(tagName, commitCount, hash, branchName)
         }
 
         project.tasks.create('printVersion') {

src/main/groovy/com/palantir/gradle/gitversion/VersionDetails.groovy

@@ -29,11 +29,13 @@ class VersionDetails implements Serializable {
     final String lastTag;
     final int commitDistance;
     final String gitHash;
+    final String branchName;
 
-    public VersionDetails(String lastTag, int commitDistance, String gitHash) {
+    public VersionDetails(String lastTag, int commitDistance, String gitHash, String branchName) {
         this.lastTag = lastTag;
         this.commitDistance = commitDistance;
         this.gitHash = gitHash;
+        this.branchName = branchName
     }
 
 }

src/test/groovy/com/palantir/gradle/gitversion/GitVersionPluginTests.groovy

@@ -238,6 +238,7 @@ class GitVersionPluginTests extends Specification {
                 println versionDetails().lastTag
                 println versionDetails().commitDistance
                 println versionDetails().gitHash
+                println versionDetails().branchName
             }
         '''.stripIndent()
         gitIgnoreFile << 'build'
@@ -250,7 +251,7 @@ class GitVersionPluginTests extends Specification {
         BuildResult buildResult = with('printVersionDetails').build()
 
         then:
-        buildResult.output =~ ":printVersionDetails\n1.0.0\n0\n[a-z0-9]{10}\n"
+        buildResult.output =~ ":printVersionDetails\n1.0.0\n0\n[a-z0-9]{10}\nmaster\n"
     }
 
     def 'version details when commit distance to tag is > 0' () {
@@ -264,6 +265,7 @@ class GitVersionPluginTests extends Specification {
                 println versionDetails().lastTag
                 println versionDetails().commitDistance
                 println versionDetails().gitHash
+                println versionDetails().branchName
             }
 
         '''.stripIndent()
@@ -278,7 +280,37 @@ class GitVersionPluginTests extends Specification {
         BuildResult buildResult = with('printVersionDetails').build()
 
         then:
-        buildResult.output =~ ":printVersionDetails\n1.0.0\n1\n[a-z0-9]{10}\n"
+        buildResult.output =~ ":printVersionDetails\n1.0.0\n1\n[a-z0-9]{10}\nmaster\n"
+    }
+
+    def 'version details when detached HEAD mode' () {
+        given:
+        buildFile << '''
+            plugins {
+                id 'com.palantir.git-version'
+            }
+            version gitVersion()
+            task printVersionDetails() << {
+                println versionDetails().lastTag
+                println versionDetails().commitDistance
+                println versionDetails().gitHash
+                println versionDetails().branchName
+            }
+
+        '''.stripIndent()
+        gitIgnoreFile << 'build'
+        Git git = Git.init().setDirectory(projectDir).call();
+        git.add().addFilepattern('.').call()
+        def commit1 = git.commit().setMessage('initial commit').call()
+        git.tag().setAnnotated(true).setMessage('1.0.0').setName('1.0.0').call()
+        git.commit().setMessage('commit 2').call()
+        git.checkout().setName(commit1.getId().getName()).call()
+
+        when:
+        BuildResult buildResult = with('printVersionDetails').build()
+
+        then:
+        buildResult.output =~ ":printVersionDetails\n1.0.0\n0\n[a-z0-9]{10}\nnull\n"
     }
 
     private GradleRunner with(String... tasks) {