Add function to parse pi number from hostname

Change-Id: Ie3f01d98e368816a3e58abe3d7639d4243a44012
diff --git a/aos/network/team_number_test.cc b/aos/network/team_number_test.cc
index c11f0a0..68727e2 100644
--- a/aos/network/team_number_test.cc
+++ b/aos/network/team_number_test.cc
@@ -6,8 +6,8 @@
 namespace network {
 namespace testing {
 
-using team_number_internal::ParseRoborioTeamNumber;
 using team_number_internal::ParsePiTeamNumber;
+using team_number_internal::ParseRoborioTeamNumber;
 
 TEST(TeamNumberTest, Parse2015TeamNumber) {
   EXPECT_EQ(971u, *ParseRoborioTeamNumber("roboRIO-971"));
@@ -39,6 +39,14 @@
   EXPECT_FALSE(ParseRoborioTeamNumber("pi-"));
   EXPECT_FALSE(ParseRoborioTeamNumber("pi-971"));
   EXPECT_FALSE(ParseRoborioTeamNumber("pi-971a-1"));
+
+  EXPECT_EQ(1u, *ParsePiNumber("pi-971-1"));
+  EXPECT_EQ(22u, *ParsePiNumber("pi-8971-22"));
+
+  EXPECT_FALSE(ParsePiNumber("pi-8971-"));
+  EXPECT_FALSE(ParsePiNumber("pi"));
+  EXPECT_FALSE(ParsePiNumber("pi-"));
+  EXPECT_FALSE(ParsePiNumber("pi-971"));
 }
 
 }  // namespace testing