Support COVERALLS_PARALLEL for parallel builds

This sets the optional parallel field in the coverage API, allowing
people to upload from multiple jobs in parallel. There's an API
endpoint that needs to be posted once all jobs are finished.

Fixes: scoverage#125

README.md

@@ -126,6 +126,24 @@ To specify encoding, add the following to your `build.sbt`
 scalacOptions += Seq("-encoding", "UTF-8")
 ```
 
+## Uploading coverage from multiple jobs in parallel
+
+Coveralls supports multiple CI jobs recording and uploading coverage, if a special flag is set and [a webhook](https://docs.coveralls.io/parallel-build-webhook) is posted once all jobs are complete.
+
+### Put the flag directly in your `build.sbt`
+
+``` scala
+import org.scoverage.coveralls.Imports.CoverallsKeys._
+
+coverallsParallel := true
+```
+
+### Add an environment variable
+
+Add an environment variable `COVERALLS_PARALLEL`, for example:
+
+    export COVERALLS_PARALLEL=true
+
 ## Using Travis-Pro
 
 It is important to set the correct `service_name` when using Travis-Pro.  The default is to use `travis-ci`.  To override this value, add the following to your `build.sbt`

src/main/scala/org/scoverage/coveralls/CoverallPayloadWriter.scala

@@ -12,6 +12,7 @@ class CoverallPayloadWriter(
     repoToken: Option[String],
     travisJobId: Option[String],
     serviceName: Option[String],
+    parallel: Boolean,
     gitClient: GitClient) {
 
   val repoRootDirStr = repoRootDir.getCanonicalPath.replace(File.separator, "/") + "/"
@@ -35,6 +36,7 @@ class CoverallPayloadWriter(
     writeOpt("service_name", serviceName)
     writeOpt("service_job_id", travisJobId)
     writeOpt("service_pull_request", sys.env.get("CI_PULL_REQUEST"))
+    gen.writeBooleanField("parallel", parallel)
 
     addGitInfo
 

src/main/scala/org/scoverage/coveralls/CoverallsPlugin.scala

@@ -22,6 +22,7 @@ object Imports {
     val coverallsEncoding = SettingKey[String]("encoding")
     val coverallsEndpoint = SettingKey[Option[String]]("coverallsEndpoint")
     val coverallsGitRepoLocation = SettingKey[Option[String]]("coveralls-git-repo")
+    val coverallsParallel = SettingKey[Boolean]("coverallsParallel")
   }
 }
 
@@ -46,7 +47,8 @@ object CoverallsPlugin extends AutoPlugin {
     coverallsServiceName := travisJobIdent map { _ => "travis-ci" },
     coverallsFile := crossTarget.value / "coveralls.json",
     coberturaFile := crossTarget.value / "coverage-report" / "cobertura.xml",
-    coverallsGitRepoLocation := Some(".")
+    coverallsGitRepoLocation := Some("."),
+    coverallsParallel := sys.env.get("COVERALLS_PARALLEL") == Some("true")
   )
 
   val aggregateFilter = ScopeFilter(inAggregates(ThisProject), inConfigurations(Compile)) // must be outside of the 'coverageAggregate' task (see: https://github.com/sbt/sbt/issues/1095 or https://github.com/sbt/sbt/issues/780)
@@ -83,6 +85,7 @@ object CoverallsPlugin extends AutoPlugin {
       repoToken,
       travisJobIdent,
       coverallsServiceName.value,
+      coverallsParallel.value,
       new GitClient(repoRootDirectory)(log)
     )
 

src/test/scala/com/github/theon/coveralls/CoverallPayloadWriterTest.scala

@@ -21,8 +21,8 @@ class CoverallPayloadWriterTest extends WordSpec with BeforeAndAfterAll with Mat
     }
   }
 
-  def coverallsWriter(writer: Writer, tokenIn: Option[String], travisJobIdIn: Option[String], serviceName: Option[String]) =
-    new CoverallPayloadWriter(new File("").getAbsoluteFile, new File(""), tokenIn, travisJobIdIn, serviceName, testGitClient) {
+  def coverallsWriter(writer: Writer, tokenIn: Option[String], travisJobIdIn: Option[String], serviceName: Option[String], parallel: Boolean) =
+    new CoverallPayloadWriter(new File("").getAbsoluteFile, new File(""), tokenIn, travisJobIdIn, serviceName, parallel, testGitClient) {
       override def generator(file: File) = {
         val factory = new JsonFactory()
         factory.createGenerator(writer)
@@ -36,35 +36,35 @@ class CoverallPayloadWriterTest extends WordSpec with BeforeAndAfterAll with Mat
 
       "generate a correct starting payload with travis job id" in {
         val w = new StringWriter()
-        val coverallsW = coverallsWriter(w, Some("testRepoToken"), Some("testTravisJob"), Some("travis-ci"))
+        val coverallsW = coverallsWriter(w, Some("testRepoToken"), Some("testTravisJob"), Some("travis-ci"), false)
 
         coverallsW.start
         coverallsW.flush()
 
         w.toString should equal(
-          """{"repo_token":"testRepoToken","service_name":"travis-ci","service_job_id":"testTravisJob",""" +
+          """{"repo_token":"testRepoToken","service_name":"travis-ci","service_job_id":"testTravisJob","parallel":false,""" +
             expectedGit +
             ""","source_files":["""
         )
       }
 
       "generate a correct starting payload without travis job id" in {
         val w = new StringWriter()
-        val coverallsW = coverallsWriter(w, Some("testRepoToken"), None, None)
+        val coverallsW = coverallsWriter(w, Some("testRepoToken"), None, None, false)
 
         coverallsW.start
         coverallsW.flush()
 
         w.toString should equal(
-          """{"repo_token":"testRepoToken",""" +
+          """{"repo_token":"testRepoToken","parallel":false,""" +
             expectedGit +
             ""","source_files":["""
         )
       }
 
       "add source files correctly" in {
         val w = new StringWriter()
-        val coverallsW = coverallsWriter(w, Some("testRepoToken"), None, Some("travis-ci"))
+        val coverallsW = coverallsWriter(w, Some("testRepoToken"), None, Some("travis-ci"), false)
 
         val projectRoot = new File("").getAbsolutePath.replace(File.separator, "/") + "/"
 
@@ -80,13 +80,27 @@ class CoverallPayloadWriterTest extends WordSpec with BeforeAndAfterAll with Mat
 
       "end the file correctly" in {
         val w = new StringWriter()
-        val coverallsW = coverallsWriter(w, Some("testRepoToken"), None, Some("travis-ci"))
+        val coverallsW = coverallsWriter(w, Some("testRepoToken"), None, Some("travis-ci"), false)
 
         coverallsW.start
         coverallsW.end()
 
         w.toString should endWith("]}")
       }
+
+      "include parallel correctly" in {
+        val w = new StringWriter()
+        val coverallsW = coverallsWriter(w, Some("testRepoToken"), None, None, true)
+
+        coverallsW.start
+        coverallsW.flush()
+
+        w.toString should equal(
+          """{"repo_token":"testRepoToken","parallel":true,""" +
+            expectedGit +
+            ""","source_files":["""
+        )
+      }
     }
   }
 }