[SPARK-17376][SPARKR] Spark version should be available in R

## What changes were proposed in this pull request?

Add sparkR.version() API.

```
> sparkR.version()
[1] "2.1.0-SNAPSHOT"
```

## How was this patch tested?

manual, unit tests

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #14935 from felixcheung/rsparksessionversion.

3 files changed, 32 insertions, 6 deletions

diff --git a/R/pkg/NAMESPACE b/R/pkg/NAMESPACE
index 5e625b2d8d..ce41b512a4 100644
--- a/R/pkg/NAMESPACE
+++ b/R/pkg/NAMESPACE
@@ -15,8 +15,15 @@ export("sparkR.init")
 export("sparkR.stop")
 export("sparkR.session.stop")
 export("sparkR.conf")
+export("sparkR.version")
 export("print.jobj")
 
+export("sparkR.newJObject")
+export("sparkR.callJMethod")
+export("sparkR.callJStatic")
+
+export("install.spark")
+
 export("sparkRSQL.init",
        "sparkRHive.init")
 
@@ -363,9 +370,3 @@ S3method(structField, character)
 S3method(structField, jobj)
 S3method(structType, jobj)
 S3method(structType, structField)
-
-export("sparkR.newJObject")
-export("sparkR.callJMethod")
-export("sparkR.callJStatic")
-
-export("install.spark")
diff --git a/R/pkg/R/SQLContext.R b/R/pkg/R/SQLContext.R
index 572e71e25b..a1404543be 100644
--- a/R/pkg/R/SQLContext.R
+++ b/R/pkg/R/SQLContext.R
@@ -156,6 +156,25 @@ sparkR.conf <- function(key, defaultValue) {
   }
 }
 
+#' Get version of Spark on which this application is running
+#'
+#' Get version of Spark on which this application is running.
+#'
+#' @return a character string of the Spark version
+#' @rdname sparkR.version
+#' @name sparkR.version
+#' @export
+#' @examples
+#'\dontrun{
+#' sparkR.session()
+#' version <- sparkR.version()
+#' }
+#' @note sparkR.version since 2.1.0
+sparkR.version <- function() {
+  sparkSession <- getSparkSession()
+  callJMethod(sparkSession, "version")
+}
+
 getDefaultSqlSource <- function() {
   l <- sparkR.conf("spark.sql.sources.default", "org.apache.spark.sql.parquet")
   l[["spark.sql.sources.default"]]
diff --git a/R/pkg/inst/tests/testthat/test_sparkSQL.R b/R/pkg/inst/tests/testthat/test_sparkSQL.R
index 683a15cb4f..aac3f62204 100644
--- a/R/pkg/inst/tests/testthat/test_sparkSQL.R
+++ b/R/pkg/inst/tests/testthat/test_sparkSQL.R
@@ -2507,6 +2507,12 @@ test_that("enableHiveSupport on SparkSession", {
   expect_equal(value, "hive")
 })
 
+test_that("Spark version from SparkSession", {
+  ver <- callJMethod(sc, "version")
+  version <- sparkR.version()
+  expect_equal(ver, version)
+})
+
 unlink(parquetPath)
 unlink(orcPath)
 unlink(jsonPath)