Add validation that query and table cannot be specified at the same t…

…ime for SpannerIO.read() (#31570)

sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/spanner/SpannerIO.java

@@ -886,6 +886,10 @@ public PCollection<Struct> expand(PBegin input) {
 
       if (getReadOperation().getQuery() != null) {
         // TODO: validate query?
+        if (getReadOperation().getTable() != null) {
+          throw new IllegalArgumentException(
+              "Both query and table cannot be specified at the same time for SpannerIO.read().");
+        }
       } else if (getReadOperation().getTable() != null) {
         // Assume read
         checkNotNull(
@@ -898,7 +902,7 @@ public PCollection<Struct> expand(PBegin input) {
                 + " list of columns to set with withColumns method");
       } else {
         throw new IllegalArgumentException(
-            "SpannerIO.read() requires configuring query or read operation.");
+            "SpannerIO.read() requires query OR table to set with withTable OR withQuery method.");
       }
 
       ReadAll readAll =

sdks/java/io/google-cloud-platform/src/test/java/org/apache/beam/sdk/io/gcp/spanner/SpannerIOReadTest.java

@@ -65,6 +65,7 @@
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
 import org.mockito.Mockito;
@@ -86,6 +87,8 @@ public class SpannerIOReadTest implements Serializable {
   public final transient TestPipeline pipeline =
       TestPipeline.create().enableAbandonedNodeEnforcement(false);
 
+  @Rule public transient ExpectedException thrown = ExpectedException.none();
+
   private FakeServiceFactory serviceFactory;
   private BatchReadOnlyTransaction mockBatchTx;
   private Partition fakePartition;
@@ -140,6 +143,22 @@ public void runBatchQueryTestWithSpannerConfig() {
             .withTimestampBound(TIMESTAMP_BOUND));
   }
 
+  @Test
+  public void runWithQueryAndWithTableAtTheSameTimeFails() {
+    SpannerIO.Read read =
+        SpannerIO.read()
+            .withSpannerConfig(spannerConfig)
+            .withQuery(QUERY_STATEMENT)
+            .withQueryName(QUERY_NAME)
+            .withTable(TABLE_ID)
+            .withColumns("id", "name")
+            .withTimestampBound(TIMESTAMP_BOUND);
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage(
+        "Both query and table cannot be specified at the same time for SpannerIO.read().");
+    runBatchQueryTest(read);
+  }
+
   @Test
   public void runBatchQueryTestWithUnspecifiedProject() {
     // Default spannerConfig has project ID specified - use an unspecified project.