Don't check for file existence in tests.

Author: rmehta19

s2a/src/test/java/io/grpc/s2a/S2AChannelCredentialsTest.java

@@ -23,7 +23,6 @@
 import io.grpc.InsecureChannelCredentials;
 import io.grpc.TlsChannelCredentials;
 import java.io.File;
-import java.io.IOException;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -129,17 +128,8 @@ private static ChannelCredentials getTlsChannelCredentials() throws Exception {
     String certChainPath = "src/test/resources/client_cert.pem";
     String trustBundlePath = "src/test/resources/root_cert.pem";
     File privateKeyFile = new File(privateKeyPath);
-    if (!privateKeyFile.exists()) {
-      throw new IOException(privateKeyPath + " does not exist");
-    }
     File certChainFile = new File(certChainPath);
-    if (!certChainFile.exists()) {
-      throw new IOException(certChainPath + " does not exist");
-    }
     File trustBundleFile = new File(trustBundlePath);
-    if (!trustBundleFile.exists()) {
-      throw new IOException(trustBundlePath + " does not exist");
-    }
     return TlsChannelCredentials.newBuilder()
       .keyManager(certChainFile, privateKeyFile)
       .trustManager(trustBundleFile)

s2a/src/test/java/io/grpc/s2a/handshaker/IntegrationTest.java

@@ -45,7 +45,6 @@
 import io.netty.handler.ssl.SslProvider;
 import java.io.ByteArrayInputStream;
 import java.io.File;
-import java.io.IOException;
 import java.util.concurrent.FutureTask;
 import java.util.logging.Logger;
 import javax.net.ssl.SSLException;
@@ -210,17 +209,8 @@ public void clientCommunicateUsingMtlsToS2ACredentials_succeeds() throws Excepti
     String certChainPath = "src/test/resources/client_cert.pem";
     String trustBundlePath = "src/test/resources/root_cert.pem";
     File privateKeyFile = new File(privateKeyPath);
-    if (!privateKeyFile.exists()) {
-      throw new IOException(privateKeyPath + " does not exist");
-    }
     File certChainFile = new File(certChainPath);
-    if (!certChainFile.exists()) {
-      throw new IOException(certChainPath + " does not exist");
-    }
     File trustBundleFile = new File(trustBundlePath);
-    if (!trustBundleFile.exists()) {
-      throw new IOException(trustBundlePath + " does not exist");
-    }
     ChannelCredentials s2aChannelCredentials =
         TlsChannelCredentials.newBuilder()
           .keyManager(certChainFile, privateKeyFile)