Add jacocoRootReport task to build.gradle

with the correct parameters to collect the jacocoReports from all
subprojects and put the jacocoTestReport.xml in the right place, so that
the coveralls plugin is able to find it.

.travis.yml

@@ -6,4 +6,4 @@ install: gradle assemble
 script: gradle check
 
 after_success:
-- gradle jacocoTestReport coveralls
+- gradle jacocoRootReport coveralls

build.gradle

@@ -18,6 +18,7 @@ apply from: 'version.gradle'
 allprojects {
 	apply plugin: 'java'
 	apply plugin: 'eclipse'
+	apply plugin: 'jacoco'
 
 	ext {
 		gitCommit = getGitCommit()
@@ -35,6 +36,23 @@ allprojects {
 		// build, causing unnecessary rebuilds.
 		builtDate = (new java.text.SimpleDateFormat("yyyy-MM-dd")).format(new Date())
 		oneLineDesc = 'An Open Source XMPP (Jabber) client library'
+		// A dirty hack used for Gradle's jacoco plugin, since is not
+		// hable to handle the case when a (sub)project has no unit
+		// tests. :-(
+		projectsWithoutUnitTests = [
+			':smack-android',
+			':smack-android-extensions',
+			':smack-bosh',
+			':smack-compression-jzlib',
+			':smack-debug',
+			':smack-debug-slf4j',
+			':smack-java7',
+			':smack-jingle-old',
+			':smack-resolver-dnsjava',
+			':smack-resolver-javax',
+			':smack-resolver-minidns',
+		].collect{ project(it) }
+		projectsWithUnitTests = subprojects - projectsWithoutUnitTests
 		androidProjects = [
 			':smack-tcp',
 			':smack-bosh',
@@ -79,6 +97,8 @@ allprojects {
 	}
 
 	repositories {
+		mavenLocal()
+		mavenCentral()
 		// Add OSS Sonatype Snapshot repository
 		maven {
 			url 'https://oss.sonatype.org/content/repositories/snapshots'
@@ -97,6 +117,19 @@ allprojects {
 			options.addStringOption('Xdoclint:none', '-quiet')
 		}
 	}
+
+	jacoco {
+		toolVersion = "0.7.4.201502262128"
+	}
+
+	jacocoTestReport {
+		dependsOn test
+		sourceDirectories = project.files(sourceSets.main.allSource.srcDirs)
+		classDirectories =  project.files(sourceSets.main.output)
+		reports {
+			xml.enabled true
+		}
+	}
 }
 
 gradle.taskGraph.whenReady { taskGraph ->
@@ -182,17 +215,11 @@ subprojects {
 	apply plugin: 'osgi'
 	apply plugin: 'signing'
 	apply plugin: 'checkstyle'
-	apply plugin: 'jacoco'
 	apply plugin: 'org.kordamp.gradle.clirr'
-	apply plugin: "com.github.kt3k.coveralls"
 
 	checkstyle {
 		configFile = new File(rootConfigDir, 'checkstyle.xml')
 	}
-	repositories {
-		mavenLocal()
-		mavenCentral()
-	}
 	task sourcesJar(type: Jar, dependsOn: classes) {
 		classifier = 'sources'
 		from sourceSets.main.allSource
@@ -289,19 +316,6 @@ subprojects {
 		baseline = [group, name, clirrBaseline].join(':')
 		failOnErrors clirrFailOnErrors
 	}
-
-	jacoco {
-		toolVersion = "0.7.1.201405082137"
-	}
-
-	jacocoTestReport {
-		dependsOn test
-		sourceDirectories = project.files(sourceSets.main.allSource.srcDirs)
-		classDirectories =  project.files(sourceSets.main.output)
-		reports {
-			xml.enabled true
-		}
-	}
 }
 
 subprojects*.jar {
@@ -310,6 +324,27 @@ subprojects*.jar {
    }
 }
 
+apply plugin: "com.github.kt3k.coveralls"
+coveralls {
+	sourceDirs = files(subprojects.sourceSets.main.allSource.srcDirs).files.absolutePath
+}
+
+task jacocoRootReport(type: org.gradle.testing.jacoco.tasks.JacocoReport) {
+	dependsOn = projectsWithUnitTests.jacocoTestReport
+	sourceDirectories = files(projectsWithUnitTests.sourceSets.main.allSource.srcDirs)
+	classDirectories = files(projectsWithUnitTests.sourceSets.main.output)
+	executionData = files(projectsWithUnitTests.jacocoTestReport.executionData)
+	reports {
+		xml.enabled true
+		xml.destination ="${buildDir}/reports/jacoco/test/jacocoTestReport.xml"
+	}
+	// We could remove the following setOnlyIf line, but then
+	// jacocoRootReport would silently be SKIPPED if something with
+	// the projectsWithUnitTests is wrong (e.g. a project is missing
+	// in there).
+	setOnlyIf { true }
+}
+
 // Important to specify this task after the subprojects block
 task clirrRootReport(type: org.kordamp.gradle.clirr.ClirrReportTask) {
 	dependsOn = subprojects.tasks.clirr