basic validation on the preferred regions. (Azure#17176)

* basic preferred regions validation

* add missing test file

Author: moderakh

sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/CosmosClientBuilder.java

@@ -9,10 +9,15 @@
 import com.azure.cosmos.implementation.ConnectionPolicy;
 import com.azure.cosmos.implementation.CosmosAuthorizationTokenResolver;
 import com.azure.cosmos.implementation.apachecommons.lang.StringUtils;
+import com.azure.cosmos.implementation.guava25.base.Preconditions;
+import com.azure.cosmos.implementation.routing.LocationHelper;
 import com.azure.cosmos.models.CosmosPermissionProperties;
 
+import java.net.URI;
+import java.net.URISyntaxException;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 import java.util.Objects;
 
 /**
@@ -736,6 +741,24 @@ private void buildConnectionPolicy() {
     }
 
     private void validateConfig() {
+        URI uri;
+        try {
+            uri = new URI(serviceEndpoint);
+        } catch (URISyntaxException e) {
+            throw new IllegalArgumentException("invalid serviceEndpoint", e);
+        }
+
+        if (preferredRegions != null) {
+            // validate preferredRegions
+            preferredRegions.stream().forEach(
+                preferredRegion -> {
+                    Preconditions.checkArgument(StringUtils.trimToNull(preferredRegion) != null, "preferredRegion can't be empty");
+                    String trimmedPreferredRegion = preferredRegion.toLowerCase(Locale.ROOT).replace(" ", "");
+                    LocationHelper.getLocationEndpoint(uri, trimmedPreferredRegion);
+                }
+            );
+        }
+
         ifThrowIllegalArgException(this.serviceEndpoint == null,
             "cannot buildAsyncClient client without service endpoint");
         ifThrowIllegalArgException(

sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/routing/LocationHelper.java

@@ -4,6 +4,7 @@
 package com.azure.cosmos.implementation.routing;
 
 import com.azure.cosmos.implementation.apachecommons.lang.StringUtils;
+import com.azure.cosmos.implementation.guava27.Strings;
 
 import java.net.URI;
 
@@ -40,7 +41,7 @@ public static URI getLocationEndpoint(URI serviceEndpoint, String location) {
                     serviceEndpoint.getPath(), serviceEndpoint.getQuery(),
                     serviceEndpoint.getFragment());
         } catch (Exception e) {
-            throw new RuntimeException(e);
+            throw new RuntimeException(Strings.lenientFormat("invalid location [%s] or serviceEndpoint [%s]", location, serviceEndpoint.toString()), e);
         }
     }
 

sdk/cosmos/azure-cosmos/src/test/java/com/azure/cosmos/CosmosClientBuilderTest.java

@@ -0,0 +1,47 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+package com.azure.cosmos;
+
+import com.azure.cosmos.implementation.TestConfigurations;
+import com.google.common.collect.ImmutableList;
+import org.testng.annotations.Test;
+
+import java.net.URISyntaxException;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class CosmosClientBuilderTest {
+
+    String hostName = "https://sample-account.documents.azure.com:443/";
+
+    @Test(groups = "unit")
+    public void validateBadPreferredRegions1() {
+        try {
+            CosmosAsyncClient client = new CosmosClientBuilder()
+                .key(TestConfigurations.MASTER_KEY)
+                .endpoint(hostName)
+                .preferredRegions(ImmutableList.of("westus1,eastus1"))
+                .buildAsyncClient();
+            client.close();
+        } catch (Exception e) {
+            assertThat(e).isInstanceOf(RuntimeException.class);
+            assertThat(e).hasCauseExactlyInstanceOf(URISyntaxException.class);
+            assertThat(e.getMessage()).isEqualTo("invalid location [westus1,eastus1] or serviceEndpoint [https://sample-account.documents.azure.com:443/]");
+        }
+    }
+
+    @Test(groups = "unit")
+    public void validateBadPreferredRegions2() {
+        try {
+            CosmosAsyncClient client = new CosmosClientBuilder()
+                .key(TestConfigurations.MASTER_KEY)
+                .endpoint(hostName)
+                .preferredRegions(ImmutableList.of(" "))
+                .buildAsyncClient();
+            client.close();
+        } catch (Exception e) {
+            assertThat(e).isInstanceOf(RuntimeException.class);
+            assertThat(e.getMessage()).isEqualTo("preferredRegion can't be empty");
+        }
+    }
+}