Define multiple test suites under Gradle for better test performance

Tests are divided into three test suites without intra-suite conflicts.
This allows us to unset forkEvery=1 (4x improvement on my desktop) and
increase execution parallelism (additional 2x improvement on my desktop).

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221656972

gradle/README.md

@@ -15,8 +15,6 @@ the existing Nomulus source tree.
 
 Dependencies are mostly the same as in Bazel, with a few exceptions:
 
-*   org.slf4j:slf4j-simple is added to provide a logging implementation in
-    tests. Bazel does not need this.
 *   com.googlecode.java-diff-utils:diffutils is not included. Bazel needs it for
     Truth's equality check, but Gradle works fine without it.
 *   jaxb 2.2.11 is used instead of 2.3 in Bazel, since the latter breaks the
@@ -27,18 +25,22 @@ Dependencies are mostly the same as in Bazel, with a few exceptions:
 
 ### Notable Issues
 
-Only single-threaded test execution is allowed, due to race condition over
-global resources, such as the local Datastore instance, or updates to the System
-properties. This is a new problem with Gradle, which does not provide as much
-test isolation as Bazel. We are exploring solutions to this problem.
-
 Test suites (RdeTestSuite and TmchTestSuite) are ignored to avoid duplicate
 execution of tests. Neither suite performs any shared test setup routine, so it
-is easier to exclude the suite classes than individual test classes.
+is easier to exclude the suite classes than individual test classes. This is the
+reason why all test tasks in the :core project contain the exclude pattern
+'"**/*TestCase.*", "**/*TestSuite.*"'
 
-Since Gradle does not support hierarchical build files, all file sets (e.g.,
-resources) must be declared at the top, in root project config or the
-sub-project configs.
+Many Nomulus tests are not hermetic: they modify global state (e.g., the shared
+local instance of Datastore) but do not clean up on completion. This becomes a
+problem with Gradle. In the beginning we forced Gradle to run every test class
+in a new process, and incurred heavy overheads. Since then, we have fixed some
+tests, and manged to divide all tests into three suites that do not have
+intra-suite conflicts. We will revisit the remaining tests soon.
+
+Note that it is unclear if all conflicting tests have been identified. More may
+be exposed if test execution order changes, e.g., when new tests are added or
+execution parallelism level changes.
 
 ## Initial Setup
 

gradle/core/build.gradle

@@ -15,6 +15,46 @@ def aptGeneratedTestDir = "${project.buildDir}/generated/source/apt/test"
 // used for easy inspection.
 def generatedDir = "${project.buildDir}/generated/source/custom/main"
 
+// Tests that conflict with (mostly unidentified) members of the main test
+// suite. It is unclear if they are offenders (i.e., those that pollute global
+// state) or victims.
+// TODO(weiminyu): identify cause and fix offending tests.
+def outcastTestPatterns = [
+    "google/registry/batch/DeleteContactsAndHostsActionTest.*",
+    "google/registry/batch/RefreshDnsOnHostRenameActionTest.*",
+    "google/registry/flows/CheckApiActionTest.*",
+    "google/registry/flows/EppLifecycleHostTest.*",
+    "google/registry/flows/domain/DomainAllocateFlowTest.*",
+    "google/registry/flows/domain/DomainApplicationCreateFlowTest.*",
+    "google/registry/flows/domain/DomainApplicationUpdateFlowTest.*",
+    "google/registry/flows/domain/DomainCreateFlowTest.*",
+    "google/registry/flows/domain/DomainUpdateFlowTest.*",
+    "google/registry/tools/server/CreatePremiumListActionTest.*",
+    // Conflicts with WhoisActionTest
+    "google/registry/whois/WhoisHttpActionTest.*",
+]
+
+// Tests that conflict with members of both the main test suite and the
+// outcast suite.
+// TODO(weiminyu): identify cause and fix offending tests.
+def fragileTestPatterns = [
+    "google/registry/cron/TldFanoutActionTest.*"
+]
+
+// Test source directories shared by all test suites.
+def testSourceDirs = [
+    "${javatestsDir}",
+    "${aptGeneratedTestDir}"
+]
+
+// Test resource directories shared by all test suites.
+def testResourceDirs = [
+    "${javatestsDir}"
+]
+
+// Exclusion pattern for test source directories shared by all test suites.
+def testResourceExclude = ['**/*.java', '**/*.xsd', '**/*.xjb']
+
 sourceSets {
   main {
     java {
@@ -33,16 +73,29 @@ sourceSets {
   }
   test {
     java {
-      srcDirs = [
-          "${javatestsDir}",
-          "${aptGeneratedTestDir}"
-      ]
+      srcDirs testSourceDirs
     }
     resources {
-      srcDirs = [
-          "${javatestsDir}"
-      ]
-      exclude '**/*.java', '**/*.xsd', '**/*.xjb'
+      srcDirs testResourceDirs
+      exclude testResourceExclude
+    }
+  }
+  fragileTest {
+    java {
+      srcDirs testSourceDirs
+    }
+    resources {
+      srcDirs testResourceDirs
+      exclude testResourceExclude
+    }
+  }
+  outcastTest {
+    java {
+      srcDirs testSourceDirs
+    }
+    resources {
+      srcDirs testResourceDirs
+      exclude testResourceExclude
     }
   }
 }
@@ -398,22 +451,34 @@ compileJava.dependsOn soyToJava
 stylesheetsToJavascript.dependsOn processResources
 classes.dependsOn stylesheetsToJavascript
 
-
-test {
-  // Test exclusion patterns:
-  // - *TestCase.java are inherited by concrete test classes.
-  // - *TestSuite.java are excluded to avoid duplicate execution of suite
-  //    members. See README in this directory for more information.
+task fragileTest(type: Test) {
+  // Common exclude pattern. See README in parent directory for explanation.
   exclude "**/*TestCase.*", "**/*TestSuite.*"
+  include fragileTestPatterns
 
-  // Use a single JVM to execute all tests. See README in this directory for
-  // more information.
-  maxParallelForks 1
-
-  // Use a single thread to execute all tests in a JVM. See README in this
-  // directory for more information.
+  // Run every test class in a freshly started process.
   forkEvery 1
 
   // Uncomment to see test outputs in stdout.
   //testLogging.showStandardStreams = true
 }
+
+task outcastTest(type: Test) {
+  // Common exclude pattern. See README in parent directory for explanation.
+  exclude "**/*TestCase.*", "**/*TestSuite.*"
+  include outcastTestPatterns
+
+  // Sets the maximum number of test executors that may exist at the same time.
+  maxParallelForks 5
+}
+
+test {
+  // Common exclude pattern. See README in parent directory for explanation.
+  exclude "**/*TestCase.*", "**/*TestSuite.*"
+  exclude fragileTestPatterns
+  exclude outcastTestPatterns
+
+  // Sets the maximum number of test executors that may exist at the same time.
+  maxParallelForks 5
+}.dependsOn(fragileTest, outcastTest)
+