DATACMNS-1820 - Moves PageabeExecutionUtils to o.s.data.support.

This avoids module cycles when it is used from a template.
The old version is still there, deprecated and delegates to the new version.

Original pull request: #472.

src/test/java/org/springframework/data/support/PageableExecutionUtilsUnitTests.java

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.support;
+
+import static java.util.Collections.*;
+import static org.assertj.core.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import java.util.Arrays;
+import java.util.function.LongSupplier;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
+
+/**
+ * Unit tests for {@link PageableExecutionUtils}.
+ *
+ * @author Mark Paluch
+ * @author Oliver Gierke
+ * @author Jens Schauder
+ */
+@ExtendWith(MockitoExtension.class)
+class PageableExecutionUtilsUnitTests {
+
+	@Mock LongSupplier totalSupplierMock;
+
+	@Test // DATAMCNS-884
+	void firstPageRequestIsLessThanOneFullPageDoesNotRequireTotal() {
+
+		Page<Integer> page = PageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), PageRequest.of(0, 10),
+				totalSupplierMock);
+
+		assertThat(page).contains(1, 2, 3);
+		assertThat(page.getTotalElements()).isEqualTo(3L);
+		verifyNoInteractions(totalSupplierMock);
+	}
+
+	@Test // DATAMCNS-884
+	void noPageableRequestDoesNotRequireTotal() {
+
+		Page<Integer> page = PageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), Pageable.unpaged(), totalSupplierMock);
+
+		assertThat(page).contains(1, 2, 3);
+		assertThat(page.getTotalElements()).isEqualTo(3L);
+
+		verifyNoInteractions(totalSupplierMock);
+	}
+
+	@Test // DATAMCNS-884
+	void subsequentPageRequestIsLessThanOneFullPageDoesNotRequireTotal() {
+
+		Page<Integer> page = PageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), PageRequest.of(5, 10),
+				totalSupplierMock);
+
+		assertThat(page).contains(1, 2, 3);
+		assertThat(page.getTotalElements()).isEqualTo(53L);
+
+		verifyNoInteractions(totalSupplierMock);
+	}
+
+	@Test // DATAMCNS-884
+	void firstPageRequestHitsUpperBoundRequiresTotal() {
+
+		doReturn(4L).when(totalSupplierMock).getAsLong();
+
+		Page<Integer> page = PageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), PageRequest.of(0, 3),
+				totalSupplierMock);
+
+		assertThat(page).contains(1, 2, 3);
+		assertThat(page.getTotalElements()).isEqualTo(4L);
+
+		verify(totalSupplierMock).getAsLong();
+	}
+
+	@Test // DATAMCNS-884
+	void subsequentPageRequestHitsUpperBoundRequiresTotal() {
+
+		doReturn(7L).when(totalSupplierMock).getAsLong();
+
+		Page<Integer> page = PageableExecutionUtils.getPage(Arrays.asList(1, 2, 3), PageRequest.of(1, 3),
+				totalSupplierMock);
+
+		assertThat(page).contains(1, 2, 3);
+		assertThat(page.getTotalElements()).isEqualTo(7L);
+
+		verify(totalSupplierMock).getAsLong();
+	}
+
+	@Test // DATAMCNS-884
+	void subsequentPageRequestWithoutResultRequiresRequireTotal() {
+
+		doReturn(7L).when(totalSupplierMock).getAsLong();
+		Page<Integer> page = PageableExecutionUtils.getPage(emptyList(), PageRequest.of(5, 10), totalSupplierMock);
+
+		assertThat(page.getTotalElements()).isEqualTo(7L);
+
+		verify(totalSupplierMock).getAsLong();
+	}
+}