A Platform family returns null from getFamily

Adding additional tests to verify this is actually true.

Author: shs96c

java/client/src/org/openqa/selenium/Platform.java

@@ -35,7 +35,7 @@ public enum Platform {
   WINDOWS("") {
     @Override
     public Platform family() {
-      return WINDOWS;
+      return null;
     }
   },
 
@@ -87,7 +87,7 @@ public Platform family() {
   MAC("mac", "darwin", "macOS", "os x") {
     @Override
     public Platform family() {
-      return MAC;
+      return null;
     }
   },
 
@@ -163,14 +163,14 @@ public String toString() {
   UNIX("solaris", "bsd") {
     @Override
     public Platform family() {
-      return UNIX;
+      return null;
     }
   },
 
   LINUX("linux") {
     @Override
     public Platform family() {
-      return LINUX;
+      return UNIX;
     }
   },
 
@@ -183,7 +183,7 @@ public Platform family() {
 
   IOS("iOS") {
     @Override
-    public Platform family() { return IOS; }
+    public Platform family() { return null; }
   },
 
   /**
@@ -346,14 +346,21 @@ private static boolean isBetterMatch(String previous, String matcher) {
    * @return true if platforms are approximately similar, false otherwise
    */
   public boolean is(Platform compareWith) {
-    return this == compareWith || this.family().is(compareWith);
+    return
+        // Any platform is itself
+        this == compareWith ||
+        // Any platform is also ANY platform
+        compareWith == ANY ||
+        // And any Platform which is not a platform type belongs to the same family
+        (this.family() != null && this.family().is(compareWith));
   }
 
   /**
    * Returns a platform that represents a family for the current platform.  For instance
    * the LINUX if a part of the UNIX family, the XP is a part of the WINDOWS family.
    *
-   * @return the family platform for the current one
+   * @return the family platform for the current one, or {@code null} if this {@code Platform}
+   *         represents a platform family (such as Windows, or MacOS)
    */
   public abstract Platform family();
 

java/client/test/org/openqa/selenium/PlatformTest.java

@@ -58,6 +58,11 @@ public void testUnixIsNotLinux() {
     assertFalse(Platform.UNIX.is(Platform.LINUX));
   }
 
+  @Test
+  public void androidIsAUnixVariant() {
+    assertTrue(Platform.ANDROID.is(Platform.UNIX));
+  }
+
   @Test
   public void testXpIsAny() {
     assertTrue(Platform.XP.is(Platform.ANY));
@@ -73,6 +78,12 @@ public void testLinuxIsAny() {
     assertTrue(Platform.LINUX.is(Platform.ANY));
   }
 
+  @Test
+  public void windowsIsNotMacOS() {
+    // Both of these are platform definitions, so return "null" for the family.
+    assertFalse(Platform.WINDOWS.is(Platform.MAC));
+  }
+
   @Test
   public void testUnixIsAny() {
     assertTrue(Platform.UNIX.is(Platform.ANY));
@@ -103,6 +114,26 @@ public void testShouldIdentifyLinux() {
     assertAllAre(Platform.LINUX, "Linux");
   }
 
+  @Test
+  public void windowsIsWindows() {
+    assertTrue(Platform.WINDOWS.is(Platform.WINDOWS));
+  }
+
+  @Test
+  public void macIsMac() {
+    assertTrue(Platform.MAC.is(Platform.MAC));
+  }
+
+  @Test
+  public void linuxIsLinux() {
+    assertTrue(Platform.LINUX.is(Platform.LINUX));
+  }
+
+  @Test
+  public void unixIsUnix() {
+    assertTrue(Platform.UNIX.is(Platform.UNIX));
+  }
+
   @Test
   public void testWindows8Detection() {
     assertEquals("Windows NT with os version 6.2 should be detected as Windows 8",