Result.match should return Result/ResultVoid (#225)

* ResultTest: group match tests and add missing errorVoid test

* Result{Void}.match() returns Result/ResultVoid

src/main/java/net/kemitix/mon/result/Err.java

@@ -67,8 +67,9 @@ class Err<T> implements Result<T> {
     }
 
     @Override
-    public void match(final Consumer<T> onSuccess, final Consumer<Throwable> onError) {
+    public Result<T> match(final Consumer<T> onSuccess, final Consumer<Throwable> onError) {
         onError.accept(error);
+        return this;
     }
 
     @Override

src/main/java/net/kemitix/mon/result/ErrVoid.java

@@ -26,11 +26,12 @@ public class ErrVoid implements ResultVoid {
     }
 
     @Override
-    public void match(
+    public ResultVoid match(
             final Runnable onSuccess,
             final Consumer<Throwable> onError
     ) {
         onError.accept(error);
+        return this;
     }
 
     @Override

src/main/java/net/kemitix/mon/result/Result.java

@@ -657,9 +657,10 @@ public interface Result<T> extends BaseResult, ThrowableFunctor<T, ThrowableFunc
      *
      * @param onSuccess the Consumer to pass the value of a successful Result to
      * @param onError   the Consumer to pass the error from an error Result to
+     * @return the original Result
      */
     @API(status = STABLE)
-    void match(Consumer<T> onSuccess, Consumer<Throwable> onError);
+    Result<T> match(Consumer<T> onSuccess, Consumer<Throwable> onError);
 
     /**
      * Provide the value within the Result, if it is a success, to the Consumer, and returns this Result.

src/main/java/net/kemitix/mon/result/ResultVoid.java

@@ -27,9 +27,10 @@ public interface ResultVoid extends BaseResult {
      *
      * @param onSuccess the Consumer to pass the value of a successful Result to
      * @param onError   the Consumer to pass the error from an error Result to
+     * @return the original ResultVoid
      */
     @API(status = STABLE)
-    void match(Runnable onSuccess, Consumer<Throwable> onError);
+    ResultVoid match(Runnable onSuccess, Consumer<Throwable> onError);
 
     /**
      * Attempts to restore an error {@code ResultVoid} to a success.

src/main/java/net/kemitix/mon/result/Success.java

@@ -62,8 +62,9 @@ class Success<T> implements Result<T> {
     }
 
     @Override
-    public void match(final Consumer<T> onSuccess, final Consumer<Throwable> onError) {
+    public Result<T> match(final Consumer<T> onSuccess, final Consumer<Throwable> onError) {
         onSuccess.accept(value);
+        return this;
     }
 
     @Override

src/main/java/net/kemitix/mon/result/SuccessVoid.java

@@ -37,8 +37,9 @@ public class SuccessVoid implements ResultVoid {
     }
 
     @Override
-    public void match(final Runnable onSuccess, final Consumer<Throwable> onError) {
+    public ResultVoid match(final Runnable onSuccess, final Consumer<Throwable> onError) {
         onSuccess.run();
+        return this;
     }
 
     @Override

src/test/java/net/kemitix/mon/ResultTest.java

@@ -106,17 +106,6 @@ class ResultTest implements WithAssertions {
             assertThat(result.isError()).isFalse();
         }
 
-        @Test
-        void whenOkayVoid_match_isNull() {
-            //when
-            var result = Result.ok();
-            //then
-            result.match(
-                    () -> assertThat(true).isTrue(),
-                    error -> fail("not an error")
-            );
-        }
-
         @Test
         void whenOk_isOkay() {
             //when
@@ -133,17 +122,6 @@ class ResultTest implements WithAssertions {
             assertThat(result.isError()).isFalse();
         }
 
-        @Test
-        void whenOkay_matchSuccess() {
-            //given
-            final Result<String> result = Result.ok("good");
-            //then
-            result.match(
-                    success -> assertThat(success).isEqualTo("good"),
-                    error -> fail("not an error")
-            );
-        }
-
         @Test
         void whenError_isError() {
             //when
@@ -160,17 +138,6 @@ class ResultTest implements WithAssertions {
             assertThat(result.isError()).isTrue();
         }
 
-        @Test
-        void whenError_matchError() {
-            //given
-            final Result<Integer> result = anError(new Exception("bad"));
-            //then
-            result.match(
-                    success -> fail("not a success"),
-                    error -> assertThat(error.getMessage()).isEqualTo("bad")
-            );
-        }
-
         @Test
         void okay_toString() {
             //given
@@ -245,6 +212,95 @@ class ResultTest implements WithAssertions {
                 .flatMap(s -> Result.of(() -> {throw e;}));
     }
 
+    @Nested
+    @DisplayName("match")
+    class MatchTests {
+
+        @Test
+        void whenOkay_matchSuccess() {
+            //given
+            Result<String> ok = Result.ok("good");
+            //then
+            ok.match(
+                    success -> assertThat(success).isEqualTo("good"),
+                    error -> fail("not an error")
+            );
+        }
+
+        @Test
+        void whenError_matchError() {
+            //given
+            Result<Integer> error = anError(new Exception("bad"));
+            //then
+            error.match(
+                    success -> fail("not a success"),
+                    e -> assertThat(e.getMessage()).isEqualTo("bad")
+            );
+        }
+
+        @Test
+        void whenOkayVoid_matchOkay() {
+            //when
+            var ok = Result.ok();
+            //then
+            ok.match(
+                    () -> assertThat(true).isTrue(),
+                    error -> fail("not an error")
+            );
+        }
+
+        @Test
+        void whenErrorVoid_matchError() {
+            //when
+            var error = Result.error(new RuntimeException());
+            //then
+            error.match(
+                    () -> fail("not a success"),
+                    e -> assertThat(true).isTrue()
+            );
+        }
+
+        @Test
+        void whenOkay_match_returnsSelf() {
+            //given
+            final Result<String> ok = Result.ok("good");
+            //when
+            Result<String> result = ok.match(s -> {}, e -> {});
+            //then
+            assertThat(result).isSameAs(ok);
+        }
+
+        @Test
+        void whenError_match_returnsSelf() {
+            //given
+            final Result<Integer> error = anError(new Exception("bad"));
+            //then
+            Result<Integer> result = error.match(s -> {}, e -> {});
+            //then
+            assertThat(result).isSameAs(error);
+        }
+
+        @Test
+        void whenOkayVoid_match_returnsSelf() {
+            //given
+            ResultVoid ok = Result.ok();
+            //when
+            ResultVoid result = ok.match(() -> {}, e -> {});
+            //then
+            assertThat(result).isSameAs(ok);
+        }
+
+        @Test
+        void whenErrorVoid_match_returnsSelf() {
+            //given
+            ResultVoid error = Result.error(new RuntimeException());
+            //when
+            ResultVoid result = error.match(() -> {}, e -> {});
+            //then
+            assertThat(result).isSameAs(error);
+        }
+    }
+
     @Nested
     @DisplayName("flatMap")
     class FlatMapTests {