added unit tests for the new introduced pattern

Author: sagnghos

src/main/java/com/google/cloud/spanner/jdbc/JdbcDriver.java

@@ -25,6 +25,7 @@
 import com.google.cloud.spanner.connection.ConnectionOptionsHelper;
 import com.google.cloud.spanner.connection.ConnectionPropertiesHelper;
 import com.google.cloud.spanner.connection.ConnectionProperty;
+import com.google.common.annotations.VisibleForTesting;
 import com.google.rpc.Code;
 import io.opentelemetry.api.OpenTelemetry;
 import java.sql.Connection;
@@ -147,8 +148,9 @@ public class JdbcDriver implements Driver {
   private static final Pattern URL_PATTERN = Pattern.compile(JDBC_URL_FORMAT);
   private static final String JDBC_EXTERNAL_HOST_FORMAT =
       "jdbc:" + ConnectionOptions.Builder.EXTERNAL_HOST_FORMAT;
-  private static final Pattern EXTERNAL_HOST_URL_PATTERN =
-      Pattern.compile(JDBC_EXTERNAL_HOST_FORMAT);
+
+  @VisibleForTesting
+  static final Pattern EXTERNAL_HOST_URL_PATTERN = Pattern.compile(JDBC_EXTERNAL_HOST_FORMAT);
 
   @InternalApi
   public static String getClientLibToken() {

src/test/java/com/google/cloud/spanner/jdbc/JdbcDriverTest.java

@@ -16,8 +16,10 @@
 
 package com.google.cloud.spanner.jdbc;
 
+import static com.google.cloud.spanner.jdbc.JdbcDriver.EXTERNAL_HOST_URL_PATTERN;
 import static com.google.common.truth.Truth.assertThat;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
@@ -47,6 +49,7 @@
 import java.util.Collection;
 import java.util.Objects;
 import java.util.Properties;
+import java.util.regex.Matcher;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
 import org.junit.Test;
@@ -211,4 +214,32 @@ public void testLenient() throws SQLException {
       assertThat(jdbc.getCode()).isEqualTo(Code.INVALID_ARGUMENT);
     }
   }
+
+  @Test
+  public void testJdbcExternalHostFormat() {
+    Matcher matcherWithoutInstance =
+        EXTERNAL_HOST_URL_PATTERN.matcher("jdbc:cloudspanner://localhost:15000/databases/test-db");
+    assertTrue(matcherWithoutInstance.matches());
+    assertEquals("test-db", matcherWithoutInstance.group("DATABASEGROUP"));
+    Matcher matcherWithProperty =
+        EXTERNAL_HOST_URL_PATTERN.matcher(
+            "jdbc:cloudspanner://localhost:15000/instances/default/databases/singers-db?usePlainText=true");
+    assertTrue(matcherWithProperty.matches());
+    assertEquals("default", matcherWithProperty.group("INSTANCEGROUP"));
+    assertEquals("singers-db", matcherWithProperty.group("DATABASEGROUP"));
+    Matcher matcherWithoutPort =
+        EXTERNAL_HOST_URL_PATTERN.matcher(
+            "jdbc:cloudspanner://localhost/instances/default/databases/test-db");
+    assertTrue(matcherWithoutPort.matches());
+    assertEquals("default", matcherWithoutPort.group("INSTANCEGROUP"));
+    assertEquals("test-db", matcherWithoutPort.group("DATABASEGROUP"));
+    Matcher matcherWithProject =
+        EXTERNAL_HOST_URL_PATTERN.matcher(
+            "jdbc:cloudspanner://localhost:15000/projects/default/instances/default/databases/singers-db");
+    assertFalse(matcherWithProject.matches());
+    Matcher matcherWithoutHost =
+        EXTERNAL_HOST_URL_PATTERN.matcher(
+            "jdbc:cloudspanner:/instances/default/databases/singers-db");
+    assertFalse(matcherWithoutHost.matches());
+  }
 }