Define ResourceResolver interface encapsulating the algorithm or strategy for resolving Resources in different contexts.

Resolves gh-92.

spring-geode/src/test/java/org/springframework/geode/core/io/ResourceResolverUnitTests.java

@@ -0,0 +1,136 @@
+/*
+ * 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.geode.core.io;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.doCallRealMethod;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import java.util.Optional;
+import java.util.Set;
+
+import org.junit.Test;
+
+import org.apache.shiro.util.CollectionUtils;
+
+import org.springframework.core.io.Resource;
+
+/**
+ * Unit Tests for {@link ResourceResolver}.
+ *
+ * @author John Blum
+ * @see org.junit.Test
+ * @see org.mockito.Mockito
+ * @see org.springframework.core.io.Resource
+ * @see org.springframework.geode.core.io.ResourceResolver
+ * @since 1.3.1
+ */
+public class ResourceResolverUnitTests {
+
+	@Test
+	public void getClassLoaderIsPresent() {
+
+		ResourceResolver resourceResolver = mock(ResourceResolver.class);
+
+		doCallRealMethod().when(resourceResolver).getClassLoader();
+
+		Set<ClassLoader> classLoaders = CollectionUtils.asSet(
+			Thread.currentThread().getContextClassLoader(),
+			getClass().getClassLoader(),
+			ClassLoader.getSystemClassLoader()
+		);
+
+		assertThat(classLoaders).contains(resourceResolver.getClassLoader().orElse(null));
+	}
+
+	@Test
+	public void requireCallsResolveReturningExistingResourceForLocation() {
+
+		String location = "/path/to/resource.dat";
+
+		Resource mockResource = mock(Resource.class);
+
+		ResourceResolver resourceResolver = mock(ResourceResolver.class);
+
+		doReturn(true).when(mockResource).exists();
+		doReturn(Optional.of(mockResource)).when(resourceResolver).resolve(eq(location));
+		doCallRealMethod().when(resourceResolver).require(any());
+
+		assertThat(resourceResolver.require(location)).isEqualTo(mockResource);
+
+		verify(resourceResolver, times(1)).resolve(eq(location));
+		verify(mockResource, times(1)).exists();
+	}
+
+	@Test(expected = IllegalStateException.class)
+	public void requireCallsResolveReturningNonExistingResourceThrowsIllegalStateException() {
+
+		String location = "/path/to/non-existing/resource.dat";
+
+		Resource mockResource = mock(Resource.class);
+
+		ResourceResolver resourceResolver = mock(ResourceResolver.class);
+
+		doReturn(false).when(mockResource).exists();
+		doReturn(Optional.of(mockResource)).when(resourceResolver).resolve(eq(location));
+		doCallRealMethod().when(resourceResolver).require(any());
+
+		try {
+			resourceResolver.require(location);
+		}
+		catch (IllegalStateException expected) {
+
+			assertThat(expected).hasMessage("Resource [%s] does not exist", location);
+			assertThat(expected).hasNoCause();
+
+			throw expected;
+		}
+		finally {
+			verify(resourceResolver, times(1)).resolve(eq(location));
+			verify(mockResource, times(1)).exists();
+		}
+	}
+
+	@Test(expected = IllegalStateException.class)
+	public void requireCallsResolveReturningNoResourceThrowsIllegalStateException() {
+
+		String location = "/path/to/nowhere";
+
+		ResourceResolver resourceResolver = mock(ResourceResolver.class);
+
+		doReturn(Optional.empty()).when(resourceResolver).resolve(eq(location));
+		doCallRealMethod().when(resourceResolver).require(any());
+
+		try {
+			resourceResolver.require(location);
+		}
+		catch (IllegalStateException expected) {
+
+			assertThat(expected).hasMessage("Resource [%s] does not exist", location);
+			assertThat(expected).hasNoCause();
+
+			throw expected;
+		}
+		finally {
+			verify(resourceResolver, times(1)).resolve(eq(location));
+		}
+	}
+}