build: DH-18477: Java coverage generated conditionally

buildSrc/src/main/groovy/TestTools.groovy

@@ -116,28 +116,6 @@ By default only runs in CI; to run locally:
                             .replace "${separator}test$separator", "$separator$type$separator"
                     (report as SimpleReport).outputLocation.set new File(rebased)
             }
-            // this is not part of the standard class; it is glued on later by jacoco plugin;
-            // we want to give each test it's own output files for jacoco analysis,
-            // so we don't accidentally stomp on previous output.
-            // TODO: verify jenkins is analyzing _all_ information here.
-            if (project.findProperty('jacoco.enabled') == "true") {
-                (t['jacoco'] as JacocoTaskExtension).with {
-                    destinationFile = project.provider({ new File(project.buildDir, "jacoco/${type}.exec".toString()) } as Callable<File>)
-                    classDumpDir = new File(project.buildDir, "jacoco/${type}Dumps".toString())
-                }
-                (project['jacocoTestReport'] as JacocoReport).with {
-                    reports {
-                        JacocoReportsContainer c ->
-                        c.xml.enabled = true
-                        c.csv.enabled = true
-                        c.html.enabled = true
-                    }
-                }
-            }
-
-        }
-        if (project.findProperty('jacoco.enabled') == "true") {
-            project.tasks.findByName('jacocoTestReport').mustRunAfter(t)
         }
 
         return t

buildSrc/src/main/groovy/io.deephaven.coverage-merge.gradle

@@ -0,0 +1,22 @@
+plugins {
+    id 'base'
+    id 'jacoco-report-aggregation'
+}
+
+jacoco {
+    toolVersion = '0.8.12'
+}
+
+tasks.register("coverage-merge", JacocoReport) {
+    def jprojects = allprojects.findAll { p-> p.plugins.hasPlugin('java') }
+    additionalSourceDirs = files(jprojects.sourceSets.main.allSource.srcDirs)
+    sourceDirectories = files(jprojects.sourceSets.main.allSource.srcDirs)
+    classDirectories = files(jprojects.sourceSets.main.output)
+    reports {
+        html.required = true
+        csv.required = true
+        xml.required = false
+    }
+    def projRootDir = project.rootDir.absolutePath
+    executionData fileTree(projRootDir).include("**/build/jacoco/*.exec")
+}

buildSrc/src/main/groovy/io.deephaven.java-jacoco-conventions.gradle

@@ -4,17 +4,24 @@ plugins {
 }
 
 jacoco {
-    toolVersion = '0.8.8'
+    toolVersion = '0.8.12'
+}
+
+test {
+    jacoco {
+        destinationFile = layout.buildDirectory.file('jacoco/jacoco.exec').get().asFile
+    }
+    finalizedBy jacocoTestReport
 }
 
 jacocoTestReport {
+    dependsOn test
     reports {
-        xml.enabled true
-        csv.enabled true
-        html.enabled true
+        csv.required = true
+        csv.destination = layout.buildDirectory.file('reports/jacoco/java-coverage.csv').get().asFile
+        xml.required = true
+        xml.outputLocation = layout.buildDirectory.file('reports/jacoco/java-coverage.xml').get().asFile
+        html.outputLocation = layout.buildDirectory.dir('reports/jacoco/html')
     }
 }
 
-project.tasks.withType(Test).all { Test t ->
-    finalizedBy jacocoTestReport
-}

buildSrc/src/main/groovy/io.deephaven.java-test-conventions.gradle

@@ -2,10 +2,10 @@ plugins {
     id 'java'
 }
 
-if (project.findProperty('jacoco.enabled') == 'true') {
-    // Only load if jacoco enabled; otherwise
-    // instrumentation of the code is still done.
+// Apply Jacoco instrumentation and coverage reporting 
+if (project.findProperty('coverage.enabled') == 'true') {
     project.apply plugin: 'io.deephaven.java-jacoco-conventions'
+    rootProject.apply plugin: 'io.deephaven.coverage-merge'
 }
 
 def testJar = project.tasks.register 'testJar', Jar, { Jar jar ->