Add AbstractRichIterableAssert scaffold and first concrete types (SetIterable and Bag)

src/main/java/org/assertj/eclipse/collections/api/AbstractRichIterableAssert.java

@@ -0,0 +1,123 @@
+/*
+ * Copyright 2025-2026 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.assertj.eclipse.collections.api;
+
+import static org.assertj.core.error.ShouldHaveSize.shouldHaveSize;
+import static org.assertj.core.util.Preconditions.checkArgument;
+
+import java.util.Objects;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+import org.assertj.core.api.AbstractAssert;
+import org.assertj.core.api.AbstractIterableAssert;
+import org.eclipse.collections.api.RichIterable;
+
+/**
+ * Base class for implementations of Eclipse Collections {@link RichIterable} assertions.
+ *
+ * @param <SELF>           the "self" type of this assertion class. Please read &quot;<a href="https://bit.ly/1IZIRcY"
+ *                         target="_blank">Emulating 'self types' using Java Generics to simplify fluent API implementation</a>&quot;
+ *                         for more details.
+ * @param <ACTUAL>         the type of the "actual" value.
+ * @param <ELEMENT>        the type of elements of the "actual" value.
+ * @param <ELEMENT_ASSERT> used for navigational assertions to return the right assert type.
+ */
+//@format:off
+public abstract class AbstractRichIterableAssert<SELF extends AbstractRichIterableAssert<SELF, ACTUAL, ELEMENT, ELEMENT_ASSERT>,
+  ACTUAL extends RichIterable<? extends ELEMENT>,
+  ELEMENT,
+  ELEMENT_ASSERT extends AbstractAssert<? extends ELEMENT_ASSERT, ELEMENT>>
+  extends AbstractIterableAssert<SELF, ACTUAL, ELEMENT, ELEMENT_ASSERT> {
+//@format:on
+
+  protected AbstractRichIterableAssert(ACTUAL actual, Class<?> selfType) {
+    super(actual, selfType);
+  }
+
+  @Override
+  public <T> SELF filteredOn(Function<? super ELEMENT, T> function, T expectedValue) {
+    checkArgument(function != null, "The filter function should not be null");
+    return internalFilteredOn(element -> Objects.equals(function.apply(element), expectedValue));
+  }
+
+  /**
+   * Filters the iterable under test keeping only elements matching the given {@link Predicate}.
+   * <p>
+   * Example: check old employees whose age &gt; 100:
+   *
+   * <pre><code class='java'> Employee yoda   = new Employee(1L, new Name("Yoda"), 800);
+   * Employee obiwan = new Employee(2L, new Name("Obiwan"), 800);
+   * Employee luke   = new Employee(3L, new Name("Luke", "Skywalker"), 26);
+   *
+   * List&lt;Employee&gt; employees = List.of(yoda, luke, obiwan);
+   *
+   * assertThat(employees).filteredOn(employee -&gt; employee.getAge() &gt; 100)
+   *                      .containsOnly(yoda, obiwan);</code></pre>
+   *
+   * @param predicate the filter predicate
+   * @return a new assertion object with the filtered iterable under test
+   * @throws IllegalArgumentException if the given predicate is {@code null}.
+   */
+  @Override
+  public SELF filteredOn(Predicate<? super ELEMENT> predicate) {
+    checkArgument(predicate != null, "The filter predicate should not be null");
+    return internalFilteredOn(predicate::test);
+  }
+
+  /**
+   * Verifies that the number of values in the actual RichIterable is equal to the given one.
+   * <p>
+   * Example:
+   * <pre>{@code
+   * // assertions will pass
+   * assertThat(Sets.immutable.of("TNG", "DS9")).hasSize(2);
+   * assertThat(Bags.immutable.of(1, 2, 3)).hasSize(3);
+   *
+   * // assertions will fail
+   * assertThat(Sets.immutable.empty()).hasSize(1);
+   * assertThat(Bags.immutable.of(1, 2, 3)).hasSize(2);
+   * }</pre>
+   *
+   * @param expected the expected number of values in the actual collection.
+   * @return {@code this} assertion object.
+   * @throws AssertionError if the number of values of the actual collection is not equal to the given one.
+   */
+  @Override
+  public SELF hasSize(int expected) {
+    isNotNull();
+
+    int actualSize = actual.size();
+    if (actualSize == expected) {
+      return myself;
+    }
+
+    throw assertionError(shouldHaveSize(actual, actualSize, expected));
+  }
+
+  /**
+   * Helper method that filters via Eclipse Collections to avoid creating any JCL collections.
+   *
+   * @param predicate The predicate to filter on.
+   * @return A new {@link AbstractRichIterableAssert} with the filtered values.
+   */
+  private SELF internalFilteredOn(org.eclipse.collections.api.block.predicate.Predicate<? super ELEMENT> predicate) {
+    checkArgument(predicate != null, "The filter predicate should not be null");
+    // TODO: In AbstractIterableAssert the withAssertionState method is package-private. Need to find out how to handle
+    //  this method or if we need to use it
+    return newAbstractIterableAssert(actual.select(predicate));//.withAssertionState(myself);
+  }
+}

src/main/java/org/assertj/eclipse/collections/api/Assertions.java

@@ -15,8 +15,10 @@
  */
 package org.assertj.eclipse.collections.api;
 
-import org.assertj.core.util.CheckReturnValue;
+import org.assertj.core.annotation.CheckReturnValue;
+import org.eclipse.collections.api.bag.Bag;
 import org.eclipse.collections.api.multimap.Multimap;
+import org.eclipse.collections.api.set.SetIterable;
 
 /**
  * Entry point for assertion methods for the Eclipse Collections library. Each method in this class is a static factory
@@ -31,6 +33,17 @@ protected Assertions() {
     // Do nothing
   }
 
+  /**
+   * Creates a new instance of {@link BagAssert}.
+   *
+   * @param actual the actual value.
+   * @return the created assertion object.
+   * @param <T> The type of the elements in the bag
+   */
+  public static <T> BagAssert<T> assertThat(Bag<T> actual) {
+    return new BagAssert<>(actual);
+  }
+
   /**
    * Creates a new instance of {@link MultimapAssert}.
    *
@@ -42,4 +55,15 @@ protected Assertions() {
   public static <KEY, VALUE> MultimapAssert<KEY, VALUE> assertThat(Multimap<KEY, VALUE> actual) {
     return new MultimapAssert<>(actual);
   }
+
+  /**
+   * Creates a new instance of {@link SetIterableAssert}.
+   *
+   * @param actual the actual value.
+   * @return the created assertion object.
+   * @param <T> The type of the elements in the set
+   */
+  public static <T>SetIterableAssert<T> assertThat(SetIterable<T> actual) {
+    return new SetIterableAssert<>(actual);
+  }
 }

src/main/java/org/assertj/eclipse/collections/api/BDDAssertions.java

@@ -15,8 +15,10 @@
  */
 package org.assertj.eclipse.collections.api;
 
-import org.assertj.core.util.CheckReturnValue;
+import org.assertj.core.annotation.CheckReturnValue;
+import org.eclipse.collections.api.bag.Bag;
 import org.eclipse.collections.api.multimap.Multimap;
+import org.eclipse.collections.api.set.SetIterable;
 
 /**
  * Behavior-driven development style entry point for assertion methods for the Eclipse Collections library. Each method
@@ -31,6 +33,17 @@ protected BDDAssertions() {
     // Do nothing
   }
 
+  /**
+   * Creates a new instance of {@link BagAssert}.
+   *
+   * @param actual the actual value.
+   * @return thre created assertion object.
+   * @param <T> THe type of the elements in the bag
+   */
+  public static <T> BagAssert<T> then(Bag<T> actual) {
+    return assertThat(actual);
+  }
+
   /**
    * Creates a new instance of {@link MultimapAssert}.
    *
@@ -42,4 +55,15 @@ protected BDDAssertions() {
   public static <KEY, VALUE> MultimapAssert<KEY, VALUE> then(Multimap<KEY, VALUE> actual) {
     return assertThat(actual);
   }
+
+  /**
+   * Creates a new instance of {@link SetIterableAssert}.
+   *
+   * @param actual the actual value.
+   * @return the created assertion object.
+   * @param <T> The type of the elements in the set
+   */
+  public static <T> SetIterableAssert<T> then(SetIterable<T> actual) {
+    return assertThat(actual);
+  }
 }

src/main/java/org/assertj/eclipse/collections/api/BagAssert.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2025-2026 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.assertj.eclipse.collections.api;
+
+import org.assertj.core.api.ObjectAssert;
+import org.eclipse.collections.api.bag.Bag;
+import org.eclipse.collections.api.bag.ImmutableBag;
+import org.eclipse.collections.api.factory.Bags;
+
+/**
+ * Assertion methods for the {@link Bag} interface.
+ *
+ * @param <ELEMENT> the type of elements stored in {@link Bag}.
+ */
+public class BagAssert<ELEMENT> extends AbstractRichIterableAssert<BagAssert<ELEMENT>, Bag<? extends ELEMENT>, ELEMENT, ObjectAssert<ELEMENT>> {
+  public BagAssert(Bag<? extends ELEMENT> elements) {
+    super(elements, BagAssert.class);
+  }
+
+  @Override
+  protected ObjectAssert<ELEMENT> toAssert(ELEMENT value) {
+    return new ObjectAssert<>(value);
+  }
+
+  @Override
+  protected BagAssert<ELEMENT> newAbstractIterableAssert(Iterable<? extends ELEMENT> iterable) {
+    ImmutableBag<? extends ELEMENT> elements = Bags.immutable.ofAll(iterable);
+    return new BagAssert<>(elements);
+  }
+}

src/main/java/org/assertj/eclipse/collections/api/EclipseCollectionsSoftAssertionsProvider.java

@@ -15,15 +15,30 @@
  */
 package org.assertj.eclipse.collections.api;
 
+import org.assertj.core.annotation.CheckReturnValue;
 import org.assertj.core.api.SoftAssertionsProvider;
-import org.assertj.core.util.CheckReturnValue;
+import org.eclipse.collections.api.bag.Bag;
 import org.eclipse.collections.api.multimap.Multimap;
+import org.eclipse.collections.api.set.SetIterable;
 
 /**
  * Soft assertions implementations for Eclipse Collections types.
  */
 @CheckReturnValue
 public interface EclipseCollectionsSoftAssertionsProvider extends SoftAssertionsProvider {
+
+  /**
+   * Create a new, proxied instance of a {@link BagAssert}
+   *
+   * @param actual the actual value
+   * @return the created assertion object
+   * @param <T> The type of the elements in the bag
+   */
+  @SuppressWarnings("unchecked")
+  default <T> BagAssert<T> assertThat(Bag<T> actual) {
+    return this.proxy(BagAssert.class, Bag.class, actual);
+  }
+
   /**
    * Creates a new, proxied instance of a {@link MultimapAssert}
    *
@@ -36,4 +51,16 @@ public interface EclipseCollectionsSoftAssertionsProvider extends SoftAssertions
   default <KEY, VALUE> MultimapAssert<KEY, VALUE> assertThat(Multimap<KEY, VALUE> actual) {
     return this.proxy(MultimapAssert.class, Multimap.class, actual);
   }
+
+  /**
+   * Creates a new, proxied instance of a {@link SetIterableAssert}
+   *
+   * @param actual the actual value
+   * @return the created assertion object
+   * @param <T> The type of the elements in the set
+   */
+  @SuppressWarnings("unchecked")
+  default <T> SetIterableAssert<T> assertThat(SetIterable<T> actual) {
+    return this.proxy(SetIterableAssert.class, SetIterable.class, actual);
+  }
 }

src/main/java/org/assertj/eclipse/collections/api/SetIterableAssert.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2025-2026 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.assertj.eclipse.collections.api;
+
+import org.assertj.core.api.ObjectAssert;
+import org.eclipse.collections.api.factory.Sets;
+import org.eclipse.collections.api.set.ImmutableSet;
+import org.eclipse.collections.api.set.SetIterable;
+
+/**
+ * Assertion methods for {@link SetIterable} interface.
+ *
+ * @param <ELEMENT> the type of elements stored in {@link SetIterable}.
+ */
+public class SetIterableAssert<ELEMENT> extends AbstractRichIterableAssert<SetIterableAssert<ELEMENT>, SetIterable<? extends ELEMENT>, ELEMENT, ObjectAssert<ELEMENT>> {
+  public SetIterableAssert(SetIterable<? extends ELEMENT> elements) {
+    super(elements, SetIterableAssert.class);
+  }
+
+  @Override
+  protected ObjectAssert<ELEMENT> toAssert(ELEMENT value) {
+    return new ObjectAssert<>(value);
+  }
+
+  @Override
+  protected SetIterableAssert<ELEMENT> newAbstractIterableAssert(Iterable<? extends ELEMENT> iterable) {
+    ImmutableSet<? extends ELEMENT> elements = Sets.immutable.ofAll(iterable);
+    return new SetIterableAssert<>(elements);
+  }
+}

src/test/java/module-info.java

@@ -17,7 +17,9 @@
  * Test module for AssertJ Eclipse Collections
  */
 open module org.assertj.eclipse.collections.test {
+  exports org.assertj.eclipse.collections.api.bag;
   exports org.assertj.eclipse.collections.api.multimap;
+  exports org.assertj.eclipse.collections.api.set;
 
   requires org.assertj.eclipse.collections;
   requires org.assertj.core;