#1341 - Added Links.addIf(boolean, Link...).

Additional unit tests to increase coverage.

Author: odrotbohm

src/main/java/org/springframework/hateoas/Links.java

@@ -76,7 +76,7 @@ public static Links of(Link... links) {
 	 * @param links
 	 */
 	public static Links of(Iterable<Link> links) {
-		return new Links(links);
+		return Links.class.isInstance(links) ? Links.class.cast(links) : new Links(links);
 	}
 
 	/**
@@ -134,6 +134,26 @@ public Links and(Link... links) {
 		return and(Arrays.asList(links));
 	}
 
+	/**
+	 * Adds the given links if the given condition is {@literal true}. The given {@link Link}s will only be resolved if
+	 * the given condition is {@literal true}. Essentially syntactic sugar to write:<br />
+	 * <code>
+	 * if (a > 3) {
+	 *   links = links.and(…);
+	 * }
+	 * </code> as <code>
+	 * links = link.andIf(a > 3, …);
+	 * </code>
+	 *
+	 * @param condition
+	 * @param links must not be {@literal null}.
+	 * @return
+	 */
+	@SafeVarargs
+	public final Links andIf(boolean condition, Link... links) {
+		return condition ? and(links) : this;
+	}
+
 	/**
 	 * Adds the given links if the given condition is {@literal true}. The given {@link Supplier}s will only be resolved
 	 * if the given condition is {@literal true}. Essentially syntactic sugar to write:<br />

src/test/java/org/springframework/hateoas/LinksUnitTest.java

@@ -143,12 +143,31 @@ void detectsContainedLinks() {
 		assertThat(Links.of(first, second).containsSameLinksAs(Links.of(first, second))).isTrue();
 	}
 
-	@Test // #1322
-	void conditionallyAddsLink() {
+	@TestFactory // #1322, #1341
+	Stream<DynamicTest> conditionallyAddsLink() {
+
+		Links links = Links.NONE;
+		Link link = Link.of("/foo");
 
-		Links links = Links.NONE.andIf(true, () -> Link.of("/foo"));
+		List<NamedLinks> adders = Arrays.asList(//
+				NamedLinks.of("adds via varargs", links.andIf(true, link)), //
+				NamedLinks.of("adds via Supplier", links.andIf(true, () -> link)), //
+				NamedLinks.of("adds via Stream", links.andIf(true, Stream.of(link))));
 
-		assertThat(links.getRequiredLink(IanaLinkRelations.SELF).getHref()).isEqualTo("/foo");
+		Stream<DynamicTest> adderTests = DynamicTest.stream(adders.iterator(), NamedLinks::getName, it -> {
+			assertThat(it.links.getRequiredLink(IanaLinkRelations.SELF).getHref()).isEqualTo("/foo");
+		});
+
+		List<NamedLinks> nonAdders = Arrays.asList(//
+				NamedLinks.of("does not add via varargs", links.andIf(false, link)), //
+				NamedLinks.of("does not add via Supplier", links.andIf(false, () -> link)), //
+				NamedLinks.of("does not add via Stream", links.andIf(false, Stream.of(link))));
+
+		Stream<DynamicTest> nonAdderTests = DynamicTest.stream(nonAdders.iterator(), NamedLinks::getName, it -> {
+			assertThat(it.links).isEmpty();
+		});
+
+		return Stream.concat(adderTests, nonAdderTests);
 	}
 
 	@Test // #1322
@@ -192,6 +211,52 @@ Stream<DynamicTest> mergesStreamOfLinks() {
 						.element(0).extracting(Link::getHref).isEqualTo("/foo"));
 	}
 
+	@TestFactory // #1340
+	Stream<DynamicTest> replacesLinksViaMerge() {
+
+		Links links = Links.of(Link.of("/foo"));
+		Link sameRel = Link.of("/bar");
+
+		List<NamedLinks> sources = Arrays.asList(//
+				NamedLinks.of("replace same rel via varargs", links.merge(MergeMode.REPLACE_BY_REL, sameRel)),
+				NamedLinks.of("replace same rel via Stream", links.merge(MergeMode.REPLACE_BY_REL, Stream.of(sameRel))));
+
+		return DynamicTest.stream(sources.iterator(), NamedLinks::getName,
+				it -> assertThat(it.links).hasSize(1) //
+						.element(0).extracting(Link::getHref).isEqualTo("/bar"));
+	}
+
+	@Test
+	void removesLinkByRel() {
+		assertThat(Links.of(Link.of("/foo")).without(IanaLinkRelations.SELF)).isEmpty();
+	}
+
+	@Test
+	void basics() {
+
+		Links none = Links.NONE;
+
+		assertThat(none.isEmpty()).isTrue();
+		assertThat(none.stream()).isEmpty();
+		assertThat(none.hasSingleLink()).isFalse();
+		assertThat(none.hasSize(0)).isTrue();
+		assertThat(none.hasLink("self")).isFalse();
+
+		Links one = none.and(Link.of("/foo"));
+
+		assertThat(one.isEmpty()).isFalse();
+		assertThat(one.stream()).isNotEmpty();
+		assertThat(one.hasSingleLink()).isTrue();
+		assertThat(one.hasSize(1)).isTrue();
+		assertThat(one.hasLink("self")).isTrue();
+
+		Links anotherOne = none.and(Link.of("/foo"));
+
+		assertThat(anotherOne).isEqualTo(one);
+		assertThat(one).isEqualTo(anotherOne);
+		assertThat(one.hashCode()).isEqualTo(anotherOne.hashCode());
+	}
+
 	@Value(staticConstructor = "of")
 	static class NamedLinks {
 		String name;