Beef up tests to test fixed-pointed-ness of Utils.resolveURI(s)

Author: andrewor14

core/src/test/scala/org/apache/spark/util/UtilsSuite.scala

@@ -204,9 +204,14 @@ class UtilsSuite extends FunSuite {
 
   test("resolveURI") {
     def assertResolves(before: String, after: String, testWindows: Boolean = false): Unit = {
-      assume(before.split(",").length == 1)
-      assert(Utils.resolveURI(before, testWindows) === new URI(after))
-      assert(Utils.resolveURI(after, testWindows) === new URI(after))
+      // This should test only single paths
+      assume(before.split(",").length === 1)
+      // Repeated invocations of resolveURI should yield the same result
+      def resolve(uri: String): String = Utils.resolveURI(uri, testWindows).toString
+      assert(resolve(after) === after)
+      assert(resolve(resolve(after)) === after)
+      assert(resolve(resolve(resolve(after))) === after)
+      // Also test resolveURIs with single paths
       assert(new URI(Utils.resolveURIs(before, testWindows)) === new URI(after))
       assert(new URI(Utils.resolveURIs(after, testWindows)) === new URI(after))
     }
@@ -222,16 +227,27 @@ class UtilsSuite extends FunSuite {
     assertResolves("file:/C:/file.txt#alias.txt", "file:/C:/file.txt#alias.txt", testWindows = true)
     intercept[IllegalArgumentException] { Utils.resolveURI("file:foo") }
     intercept[IllegalArgumentException] { Utils.resolveURI("file:foo:baby") }
+  }
 
-    // Test resolving comma-delimited paths
-    assert(Utils.resolveURIs("jar1,jar2") === s"file:$cwd/jar1,file:$cwd/jar2")
-    assert(Utils.resolveURIs("file:/jar1,file:/jar2") === "file:/jar1,file:/jar2")
-    assert(Utils.resolveURIs("hdfs:/jar1,file:/jar2,jar3") ===
-      s"hdfs:/jar1,file:/jar2,file:$cwd/jar3")
-    assert(Utils.resolveURIs("hdfs:/jar1,file:/jar2,jar3,jar4#jar5") ===
+  test("resolveURIs with multiple paths") {
+    def assertResolves(before: String, after: String, testWindows: Boolean = false): Unit = {
+      assume(before.split(",").length > 1)
+      assert(Utils.resolveURIs(before, testWindows) === after)
+      assert(Utils.resolveURIs(after, testWindows) === after)
+      // Repeated invocations of resolveURIs should yield the same result
+      def resolve(uri: String): String = Utils.resolveURIs(uri, testWindows)
+      assert(resolve(after) === after)
+      assert(resolve(resolve(after)) === after)
+      assert(resolve(resolve(resolve(after))) === after)
+    }
+    val cwd = System.getProperty("user.dir")
+    assertResolves("jar1,jar2", s"file:$cwd/jar1,file:$cwd/jar2")
+    assertResolves("file:/jar1,file:/jar2", "file:/jar1,file:/jar2")
+    assertResolves("hdfs:/jar1,file:/jar2,jar3", s"hdfs:/jar1,file:/jar2,file:$cwd/jar3")
+    assertResolves("hdfs:/jar1,file:/jar2,jar3,jar4#jar5",
       s"hdfs:/jar1,file:/jar2,file:$cwd/jar3,file:$cwd/jar4#jar5")
-    assert(Utils.resolveURIs("hdfs:/jar1,file:/jar2,jar3,C:\\pi.py#py.pi", testWindows = true) ===
-      s"hdfs:/jar1,file:/jar2,file:$cwd/jar3,file:/C:/pi.py#py.pi")
+    assertResolves("hdfs:/jar1,file:/jar2,jar3,C:\\pi.py#py.pi",
+      s"hdfs:/jar1,file:/jar2,file:$cwd/jar3,file:/C:/pi.py#py.pi", testWindows = true)
   }
 
   test("nonLocalPaths") {