Failure scenarios when dealing with lambdas

src/test/java/org/walkmod/deadcodecleaner/visitors/CleanDeadDeclarationsVisitorTest.java

@@ -487,4 +487,98 @@ public void testRemoveConditions() throws Exception {
       Assert.assertFalse(cu.getImports().isEmpty());
 
 	}
+
+	@Test
+	public void testDontRemoveImportsUsedByLambdas() throws Exception {
+		String externalClass = "package blah;" +
+				"import java.util.function.Supplier;" +
+				"public class MyClassThatNeedsToBeImported {" +
+				"public static <T> Supplier<T> memoize(Supplier<T> delegate) {" +
+				"return null;" + //Implementation not relevant to testcase
+				"}" +
+				"}";
+		String code = "package example;" +
+				"import blah.MyClassThatNeedsToBeImported;" +
+				"import java.util.function.Supplier;" +
+				"class MyClass {" +
+				"Supplier o;" +
+				"public MyClass() {" +
+				" this.o = MyClassThatNeedsToBeImported.memoize(this::load)::get;" +
+
+				"load();" +
+
+				"}" +
+				"private Object load() {" +
+				"return null;"+ //Implementation not relevant to testcase
+				"}}";
+
+		CompilationUnit cu = compile(code, externalClass);
+		String codeBefore = cu.toString();
+
+		CleanDeadDeclarationsVisitor<?> visitor = new CleanDeadDeclarationsVisitor<Object>();
+		cu.accept(visitor, null);
+		String codeAfter = cu.toString();
+
+		Assert.assertEquals(codeBefore, codeAfter);
+	}
+
+	@Test
+	public void testDontRemoveImportsUsedByLambdasExample2() throws Exception {
+		String code = "package example;" +
+"import java.util.Collection;" +
+"import java.util.Objects;" +
+"import static java.util.stream.Collectors.toSet;" +
+"		public class ExampleGroupPickerSearcher {" +
+"			public ExampleGroupPickerSearcher() {" +
+"				final Resolver<String> nameResolver = rawValues ->" +
+"						rawValues.stream()" +
+"								.map(this::convertToIndexValue)" +
+"								.filter(Objects::nonNull)" +
+"								.collect(toSet());" +
+"			}" +
+"			public String convertToIndexValue(final Object rawValue) {" +
+"				return \"\";" +
+"			}" +
+"			public interface Resolver<T> {" +
+"				Collection<T> resolveNames(Collection<Object> rawValues);" +
+"			}" +
+"		}";
+		CompilationUnit cu = compile(code);
+		String codeBefore = cu.toString();
+
+		CleanDeadDeclarationsVisitor<?> visitor = new CleanDeadDeclarationsVisitor<Object>();
+		cu.accept(visitor, null);
+		String codeAfter = cu.toString();
+
+		Assert.assertEquals(codeBefore, codeAfter);
+	}
+
+	@Test
+	public void testDontRemoveImportsUsedByLambdasExample3() throws Exception {
+		String code = "package example;" +
+"import java.util.function.Supplier;" +
+		"public class ExampleDefaultTemplateManager {" +
+			"public ExampleDefaultTemplateManager() {" +
+				"ContextFreeReference<Object> holderRef = new ContextFreeReference<>(this::initTemplates);" +
+			"}" +
+			"private Object initTemplates() {" +
+				"return null;" +
+			"}" +
+			"public class ContextFreeReference<T> implements Supplier<T> {" +
+				"public ContextFreeReference(Supplier<T> supplier) {" +
+				"}" +
+				"public T get() {" +
+					"return null;" +
+				"}" +
+			"}" +
+		"}";
+		CompilationUnit cu = compile(code);
+		String codeBefore = cu.toString();
+
+		CleanDeadDeclarationsVisitor<?> visitor = new CleanDeadDeclarationsVisitor<Object>();
+		cu.accept(visitor, null);
+		String codeAfter = cu.toString();
+
+		Assert.assertEquals(codeBefore, codeAfter);
+	}
 }