Fix prerelease property being incorrectly set on publish task (#75)

## Description

When executing a final release for a WDK project the actual github release is marked as `prerelease`. 
This is due to the predicate not being fully correct.

## Changes
* ![FIX] ReleasePlugin: Github publish task prerelease predicate
* ![ADD] gradle-commons-test test library

build.gradle

@@ -66,6 +66,7 @@ dependencies {
 
     testImplementation 'gradle.plugin.net.wooga.gradle:atlas-unity:2.0.0-rc.3'
     testImplementation 'gradle.plugin.net.wooga.gradle:atlas-wdk-unity:2.0.0-rc.3'
+    testImplementation 'com.wooga.gradle:gradle-commons-test:(0, 1]'
 
     implementation group: 'org.kohsuke', name: 'github-api', version: '1.130'
     implementation 'org.ajoberstar.grgit:grgit-core:(4.1,5]'

src/integrationTest/groovy/wooga/gradle/release/ReleasePluginIntegrationSpec.groovy

@@ -16,6 +16,7 @@
 
 package wooga.gradle.release
 
+import com.wooga.gradle.test.PropertyQueryTaskWriter
 import org.ajoberstar.grgit.Grgit
 import org.gradle.api.Task
 import org.gradle.api.specs.Spec
@@ -45,7 +46,6 @@ class ReleasePluginIntegrationSpec extends IntegrationSpec {
         createFile("paket.dependencies")
     }
 
-
 //    @Unroll("verify dependency setup to #testType unity sub-projects")
 //    def "verify dependency setup to unity sub-projects"() {
 //        given: "some subprojects with net.wooga.unity applied"
@@ -417,4 +417,30 @@ class ReleasePluginIntegrationSpec extends IntegrationSpec {
         '0.3.0-a0000'    | 300
         '12.34.200-2334' | 123600
     }
+
+    @Unroll("prerelease #expectedMessage when project status is #status")
+    def "prerelease property is set correctly on by the plugin"() {
+        given: "a buildfile with release plugin applied"
+        buildFile << """            
+            ${applyPlugin(ReleasePlugin)}
+            project.status = "${status}"
+        """.stripIndent()
+
+        when:
+        def query = new PropertyQueryTaskWriter("${GithubPublishPlugin.PUBLISH_TASK_NAME}.prerelease")
+        query.write(buildFile)
+        def result = runTasksSuccessfully(query.taskName)
+
+        then:
+        result.wasExecuted(query.taskName)
+        query.matches(result, isPrerelease)
+
+        where:
+        status    | isPrerelease
+        "final"   | false
+        "release" | false
+        "rc"      | true
+
+        expectedMessage = isPrerelease ? "set" : "not set"
+    }
 }

src/main/groovy/wooga/gradle/release/ReleasePlugin.groovy

@@ -235,7 +235,9 @@ class ReleasePlugin implements Plugin<Project> {
         githubPublishTask.dependsOn(archives)
         githubPublishTask.tagName.set("v${project.version}")
         githubPublishTask.releaseName.set(project.version.toString())
-        githubPublishTask.prerelease.set(project.provider { project.status != 'final' })
+        // Gradle defaults to 'release' for the project status, as seen here:
+        // https://docs.gradle.org/current/javadoc/org/gradle/api/Project.html#getStatus--
+        githubPublishTask.prerelease.set(project.provider { project.status != 'final' && project.status != 'release' })
 
         // Write the release description using the release notes generated by
         // the release strategy