Write struct extend unit test for struct array

Author: stevelordbq

spark-3.1-spanner-lib/src/main/java/com/google/cloud/spark/spanner/SpannerWriterUtils.java

@@ -268,6 +268,7 @@ private static Value convertField(InternalRow row, int index, DataType type) {
 
         final ArrayData arrayData = row.getArray(index);
         final int numElements = arrayData.numElements();
+        if (numElements == 0) return Value.structArray(Type.struct(), null);
         List<Struct> convertedList = new ArrayList<>(numElements);
 
         for (int j = 0; j < numElements; j++) {
@@ -280,10 +281,7 @@ private static Value convertField(InternalRow row, int index, DataType type) {
           }
         }
 
-        return Value.structArray(
-            Type.struct(Type.StructField.of("field", Type.string())),
-            convertedList); // TODO: the struct element type should represent the schema of the
-        // struct.
+        return Value.structArray(convertedList.get(0).getType(), convertedList);
       }
     }
 

spark-3.1-spanner-lib/src/test/java/com/google/cloud/spark/spanner/SpannerWriterUtilsTest.java

@@ -355,23 +355,31 @@ public static Collection<Object[]> data() {
             {
               "struct_array",
               new StructType()
-                  .add(
-                      "field",
-                      DataTypes.StringType), // Add at least one field to match getStruct(i, 1)
+                  .add("str_field", DataTypes.StringType)
+                  .add("bool_field", DataTypes.BooleanType),
               new InternalRow[] {
                 mock(InternalRow.class)
               }, // Use InternalRow instead of Spanner Struct
               Value.structArray(
-                  Type.struct(Type.StructField.of("field", Type.string())),
-                  Collections.singletonList(Struct.newBuilder().set("field").to("value").build())),
+                  Type.struct(
+                      Type.StructField.of("str_field", Type.string()),
+                      Type.StructField.of("bool_field", Type.bool())),
+                  Collections.singletonList(
+                      Struct.newBuilder()
+                          .set("str_field")
+                          .to("str_value")
+                          .set("bool_field")
+                          .to(true)
+                          .build())),
               (BiConsumer<ArrayData, Object>)
                   (ad, d) ->
                       setupArrayMock(
                           ad,
                           (InternalRow[]) d, // Cast to InternalRow array
                           (i, val) -> {
-                            when(ad.getStruct(i, 1)).thenReturn((InternalRow) val);
-                            when(((InternalRow) val).getString(0)).thenReturn("value");
+                            when(ad.getStruct(i, 2)).thenReturn((InternalRow) val);
+                            when(((InternalRow) val).getString(0)).thenReturn("str_value");
+                            when(((InternalRow) val).getBoolean(1)).thenReturn(true);
                           })
             }
           });