feat: add snapshotVersion task.

src/main/groovy/net/researchgate/release/ReleasePlugin.groovy

@@ -23,6 +23,7 @@ import net.researchgate.release.tasks.InitScmAdapter
 import net.researchgate.release.tasks.PreTagCommit
 import net.researchgate.release.tasks.PrepareVersions
 import net.researchgate.release.tasks.UnSnapshotVersion
+import net.researchgate.release.tasks.SnapshotVersion
 import net.researchgate.release.tasks.UpdateVersion
 import org.gradle.api.GradleException
 import org.gradle.api.Plugin
@@ -71,6 +72,7 @@ abstract class ReleasePlugin extends PluginHelper implements Plugin<Project> {
                 "${p}checkUpdateNeeded" as String,
                 "${p}checkoutMergeToReleaseBranch" as String,
                 "${p}unSnapshotVersion" as String,
+                "${p}snapshotVersion" as String,
                 "${p}confirmReleaseVersion" as String,
                 "${p}checkSnapshotDependencies" as String,
                 "${p}runBuildTasks" as String,
@@ -102,6 +104,7 @@ abstract class ReleasePlugin extends PluginHelper implements Plugin<Project> {
             }
         }
         project.tasks.create('unSnapshotVersion', UnSnapshotVersion.class)
+        project.tasks.create('snapshotVersion', SnapshotVersion.class)
         project.tasks.create('confirmReleaseVersion', ConfirmReleaseVersion.class)
         project.tasks.create('checkSnapshotDependencies', CheckSnapshotDependencies.class)
         project.tasks.create('runBuildTasks', GradleBuild) {

src/main/groovy/net/researchgate/release/tasks/SnapshotVersion.groovy

@@ -0,0 +1,46 @@
+package net.researchgate.release.tasks
+
+
+import org.gradle.api.GradleException
+import org.gradle.api.Project
+import org.gradle.api.tasks.TaskAction
+
+class SnapshotVersion extends BaseReleaseTask {
+
+    SnapshotVersion() {
+        super()
+        description = 'Adds "-SNAPSHOT" to project\'s current version.'
+    }
+
+    @TaskAction
+    void snapshotVersion() {
+        checkPropertiesFile(project)
+        def version = project.version.toString()
+
+        if (!version.endsWith(extension.snapshotSuffix.get())) {
+            version += extension.snapshotSuffix.get()
+            scmAdapter.updateVersionProperty(version)
+        }
+    }
+
+    void checkPropertiesFile(Project project) {
+        File propertiesFile = findPropertiesFile(project)
+
+        if (!propertiesFile.canRead() || !propertiesFile.canWrite()) {
+            throw new GradleException("Unable to update version property. Please check file permissions.")
+        }
+
+        Properties properties = new Properties()
+        propertiesFile.withReader { properties.load(it) }
+
+        assert properties.version, "[$propertiesFile.canonicalPath] contains no 'version' property"
+        assert extension.versionPatterns.keySet().any { (properties.version =~ it).find() },
+                "[$propertiesFile.canonicalPath] version [$properties.version] doesn't match any of known version patterns: " +
+                        extension.versionPatterns.keySet()
+
+        // set the project version from the properties file if it was not otherwise specified
+        if (!isVersionDefined()) {
+            project.version = properties.version
+        }
+    }
+}

src/test/groovy/net/researchgate/release/ReleasePluginTests.groovy

@@ -10,6 +10,7 @@
 
 package net.researchgate.release
 
+import net.researchgate.release.tasks.SnapshotVersion
 import net.researchgate.release.tasks.UnSnapshotVersion
 import net.researchgate.release.tasks.UpdateVersion
 import org.gradle.api.plugins.BasePlugin
@@ -103,6 +104,18 @@ class ReleasePluginTests extends Specification {
         project.version == '1.4-dev'
     }
 
+    def 'version is properly snapshoted when using default snapshot suffix'() {
+        given:
+        def testVersionPropertyFile = project.file('gradle.properties')
+        testVersionPropertyFile.withWriter { w ->
+            w.writeLine 'version=1.3'
+        }
+        when:
+        (project.tasks.snapshotVersion as SnapshotVersion).snapshotVersion()
+        then:
+        project.version == '1.3-SNAPSHOT'
+    }
+
     def 'snapshot version should be updated to new snapshot version with default snapshot suffix'() {
         given:
         def testVersionPropertyFile = project.file('gradle.properties')