feat: return result-object from instantiators

The result contains the outcome of the attempt to instantiate the class. Previously, only null was returned if the attempt failed; now the error message is being included.
Nylle · Oct 3, 2024 · f079468 · f079468
1 parent 87937b3
commit f079468
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Showing 8 changed files with 90 additions and 44 deletions.
diff --git a/src/main/java/com/github/nylle/javafixture/instantiation/BuilderInstantiator.java b/src/main/java/com/github/nylle/javafixture/instantiation/BuilderInstantiator.java
@@ -30,7 +30,7 @@ public static <T> BuilderInstantiator<T> create(Method builderMethodCandidate, S
                 .orElse(null);
     }
 
-    public T invoke(SpecimenFactory specimenFactory, CustomizationContext customizationContext) {
+    public Result<T> invoke(SpecimenFactory specimenFactory, CustomizationContext customizationContext) {
         try {
             var builder = builderMethod.invoke(null, new Object[]{});
 
@@ -42,9 +42,9 @@ public T invoke(SpecimenFactory specimenFactory, CustomizationContext customizat
                 });
             }
 
-            return (T) buildMethod.invoke(builder, new Object[]{});
+            return Result.of((T) buildMethod.invoke(builder, new Object[]{}));
         } catch (InvocationTargetException | IllegalAccessException ex) {
-            return null;
+            return Result.empty(ex.getMessage());
         }
     }
 

diff --git a/src/main/java/com/github/nylle/javafixture/instantiation/ConstructorInstantiator.java b/src/main/java/com/github/nylle/javafixture/instantiation/ConstructorInstantiator.java
@@ -5,6 +5,7 @@
 import com.github.nylle.javafixture.SpecimenType;
 
 import java.lang.annotation.Annotation;
+import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Parameter;
 import java.util.List;
 import java.util.Map;
@@ -23,13 +24,15 @@ public static <T> ConstructorInstantiator<T> create(java.lang.reflect.Constructo
         return new ConstructorInstantiator<>(constructor);
     }
 
-    public T invoke(SpecimenFactory specimenFactory, CustomizationContext customizationContext) {
+    public Result<T> invoke(SpecimenFactory specimenFactory, CustomizationContext customizationContext) {
         try {
-            return constructor.newInstance(stream(constructor.getParameters())
+            return Result.of(constructor.newInstance(stream(constructor.getParameters())
                     .map(p -> createParameter(p, specimenFactory, customizationContext))
-                    .toArray());
-        } catch(Exception ex) {
-            return null;
+                    .toArray()));
+        } catch (InvocationTargetException ex) {
+            return Result.empty(ex.getTargetException().getMessage());
+        } catch (Exception ex) {
+            return Result.empty(ex.getMessage());
         }
     }
 

diff --git a/src/main/java/com/github/nylle/javafixture/instantiation/FactoryMethodInstantiator.java b/src/main/java/com/github/nylle/javafixture/instantiation/FactoryMethodInstantiator.java
@@ -23,20 +23,18 @@ public static <T> FactoryMethodInstantiator<T> create(Method factoryMethod, Spec
         return new FactoryMethodInstantiator<>(factoryMethod, targetType);
     }
 
-    public T invoke(SpecimenFactory specimenFactory, CustomizationContext customizationContext) {
+    public Result<T> invoke(SpecimenFactory specimenFactory, CustomizationContext customizationContext) {
         try {
             List<Object> arguments = new ArrayList<>();
             for (int i = 0; i < factoryMethod.getParameterCount(); i++) {
-                var genericParameterType = factoryMethod.getGenericParameterTypes()[i];
                 var specimen = specimenFactory.build(targetType.isParameterized()
                         ? targetType.getGenericTypeArgument(i)
-                        : SpecimenType.fromClass(genericParameterType));
-                var o = specimen.create(customizationContext, new Annotation[0]);
-                arguments.add(o);
+                        : SpecimenType.fromClass(factoryMethod.getGenericParameterTypes()[i]));
+                arguments.add(specimen.create(customizationContext, new Annotation[0]));
             }
-            return (T) factoryMethod.invoke(null, arguments.toArray());
+            return Result.of((T) factoryMethod.invoke(null, arguments.toArray()));
         } catch (Exception ex) {
-            return null;
+            return Result.empty(ex.getMessage());
         }
     }
 }
diff --git a/src/main/java/com/github/nylle/javafixture/instantiation/Instantiator.java b/src/main/java/com/github/nylle/javafixture/instantiation/Instantiator.java
@@ -5,6 +5,42 @@
 
 public interface Instantiator<T> {
 
-    T invoke(SpecimenFactory specimenFactory, CustomizationContext customizationContext);
+    Result<T> invoke(SpecimenFactory specimenFactory, CustomizationContext customizationContext);
 
+    class Result<T> {
+        private T value;
+        private String message;
+
+        private Result(T value, String message) {
+            this.value = value;
+            this.message = message;
+        }
+
+        public static <T> Result<T> of(T value) {
+            if(value == null) {
+                return new Result<T>(null, "result was null");
+            }
+            return new Result<T>(value, null);
+        }
+
+        public static <T> Result<T> empty(String message) {
+            return new Result<T>(null, message);
+        }
+
+        public T getValue() {
+            return value;
+        }
+
+        public String getMessage() {
+            return message;
+        }
+
+        public boolean isPresent() {
+            return value != null;
+        }
+
+        public boolean isEmpty() {
+            return value == null;
+        }
+    }
 }
diff --git a/src/test/java/com/github/nylle/javafixture/SpecimenTypeTest.java b/src/test/java/com/github/nylle/javafixture/SpecimenTypeTest.java
@@ -2,6 +2,7 @@
 
 import com.github.nylle.javafixture.annotations.testcases.TestCase;
 import com.github.nylle.javafixture.annotations.testcases.TestWithCases;
+import com.github.nylle.javafixture.instantiation.BuilderInstantiator;
 import com.github.nylle.javafixture.testobjects.ClassWithBuilder;
 import com.github.nylle.javafixture.testobjects.ITestGeneric;
 import com.github.nylle.javafixture.testobjects.TestAbstractClass;
@@ -59,7 +60,6 @@
 import java.util.concurrent.LinkedTransferQueue;
 import java.util.concurrent.TransferQueue;
 
-import static com.github.nylle.javafixture.CustomizationContext.noContext;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 
@@ -375,14 +375,12 @@ class FindBuilders {
 
         @Test
         void returnsListOfBuilders() {
-            var specimenFactory = new SpecimenFactory(new Context(new Configuration()));
-
             var sut = new SpecimenType<ClassWithBuilder>(){};
 
             var actual = sut.findBuilders();
 
             assertThat(actual).hasSize(1);
-            assertThat(actual.get(0).invoke(specimenFactory, noContext())).isInstanceOf(ClassWithBuilder.class);
+            assertThat(actual.get(0)).isInstanceOf(BuilderInstantiator.class);
         }
 
         @TestWithCases

diff --git a/src/test/java/com/github/nylle/javafixture/instantiation/BuilderInstantiatorTest.java b/src/test/java/com/github/nylle/javafixture/instantiation/BuilderInstantiatorTest.java
@@ -18,9 +18,9 @@ void invokeReturnsBuiltObjectWithAllMethodsCalled() throws NoSuchMethodException
 
         var result = sut.invoke(new SpecimenFactory(new Context(new Configuration())), CustomizationContext.noContext());
 
-        assertThat(result).isInstanceOf(ClassWithBuilder.class);
+        assertThat(result.getValue()).isInstanceOf(ClassWithBuilder.class);
 
-        var actual = (ClassWithBuilder) result;
+        var actual = (ClassWithBuilder) result.getValue();
 
         assertThat(actual.getNumber()).isNotNull();
         assertThat(actual.getString()).isNotNull();

diff --git a/src/test/java/com/github/nylle/javafixture/instantiation/ConstructorInstantiatorTest.java b/src/test/java/com/github/nylle/javafixture/instantiation/ConstructorInstantiatorTest.java
@@ -5,6 +5,7 @@
 import com.github.nylle.javafixture.CustomizationContext;
 import com.github.nylle.javafixture.SpecimenFactory;
 import com.github.nylle.javafixture.testobjects.TestObject;
+import com.github.nylle.javafixture.testobjects.withconstructor.ConstructorExceptionAndNoFactoryMethod;
 import com.github.nylle.javafixture.testobjects.withconstructor.TestObjectWithConstructedField;
 import com.github.nylle.javafixture.testobjects.withconstructor.TestObjectWithGenericConstructor;
 import org.junit.jupiter.api.DisplayName;
@@ -25,9 +26,9 @@ void canCreateInstanceFromConstructor() throws NoSuchMethodException {
 
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), new CustomizationContext(List.of(), Map.of(), false));
 
-        assertThat(actual).isInstanceOf(TestObjectWithGenericConstructor.class);
-        assertThat(actual.getValue()).isInstanceOf(String.class);
-        assertThat(actual.getInteger()).isInstanceOf(Optional.class);
+        assertThat(actual.getValue()).isInstanceOf(TestObjectWithGenericConstructor.class);
+        assertThat(actual.getValue().getValue()).isInstanceOf(String.class);
+        assertThat(actual.getValue().getInteger()).isInstanceOf(Optional.class);
     }
 
     @Test
@@ -37,8 +38,8 @@ void fieldsNotSetByConstructorAreNull() throws NoSuchMethodException {
 
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), new CustomizationContext(List.of(), Map.of(), false));
 
-        assertThat(actual).isInstanceOf(TestObjectWithGenericConstructor.class);
-        assertThat(actual.getPrivateField()).isNull();
+        assertThat(actual.getValue()).isInstanceOf(TestObjectWithGenericConstructor.class);
+        assertThat(actual.getValue().getPrivateField()).isNull();
     }
 
     @Test
@@ -49,7 +50,7 @@ void argumentsCanBeCustomized() throws NoSuchMethodException {
         // use arg0, because .class files do not store formal parameter names by default
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), new CustomizationContext(List.of(), Map.of("arg0", "customized"), true));
 
-        assertThat(actual.getValue()).isEqualTo("customized");
+        assertThat(actual.getValue().getValue()).isEqualTo("customized");
     }
 
     @Test
@@ -59,9 +60,9 @@ void usingConstructorIsRecursive() throws NoSuchMethodException {
 
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), new CustomizationContext(List.of(), Map.of(), true));
 
-        assertThat(actual).isInstanceOf(TestObjectWithConstructedField.class);
-        assertThat(actual.getTestObjectWithGenericConstructor().getPrivateField()).isNull();
-        assertThat(actual.getNotSetByConstructor()).isNull();
+        assertThat(actual.getValue()).isInstanceOf(TestObjectWithConstructedField.class);
+        assertThat(actual.getValue().getTestObjectWithGenericConstructor().getPrivateField()).isNull();
+        assertThat(actual.getValue().getNotSetByConstructor()).isNull();
     }
 
     @Test
@@ -72,7 +73,7 @@ void constructorArgumentsAreUsedOnce() throws NoSuchMethodException {
         // use arg0, because .class files do not store formal parameter names by default
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), new CustomizationContext(List.of(), Map.of("arg0", 2), true));
 
-        assertThat(actual.getSetByConstructor()).isEqualTo(2);
+        assertThat(actual.getValue().getSetByConstructor()).isEqualTo(2);
     }
 
     @Test
@@ -83,6 +84,16 @@ void ignoredConstructorArgsAreRespected() throws NoSuchMethodException {
         // use arg0, because .class files do not store formal parameter names by default
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), new CustomizationContext(List.of("arg0"), Map.of(), true));
 
-        assertThat(actual.getSetByConstructor()).isEqualTo(0);
+        assertThat(actual.getValue().getSetByConstructor()).isEqualTo(0);
+    }
+
+    @Test
+    void xxx() throws NoSuchMethodException {
+        var sut = ConstructorInstantiator.create(ConstructorExceptionAndNoFactoryMethod.class.getConstructor());
+
+        var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), new CustomizationContext(List.of(), Map.of(), true));
+
+        assertThat(actual.isEmpty()).isTrue();
+        assertThat(actual.getMessage()).isEqualTo("expected for tests");
     }
 }
diff --git a/src/test/java/com/github/nylle/javafixture/instantiation/FactoryMethodInstantiatorTest.java b/src/test/java/com/github/nylle/javafixture/instantiation/FactoryMethodInstantiatorTest.java
@@ -27,7 +27,7 @@ void factoryMethodWithoutArgument() throws NoSuchMethodException {
 
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), noContext());
 
-        assertThat(actual.getValue()).isEqualTo(42);
+        assertThat(actual.getValue().getValue()).isEqualTo(42);
     }
 
     @Test
@@ -37,7 +37,7 @@ void returnsInstanceOfClassUsingFactoryMethodWithArguments() throws NoSuchMethod
 
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), noContext());
 
-        assertThat(actual.getValue()).isNotNull();
+        assertThat(actual.getValue().getValue()).isNotNull();
     }
 
     @Test
@@ -47,7 +47,7 @@ void factoryMethodWithGenericArgument() throws NoSuchMethodException {
 
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), noContext());
 
-        assertThat(actual.getValue()).isNotNull();
+        assertThat(actual.getValue().getValue()).isNotNull();
     }
 
     @Test
@@ -57,7 +57,7 @@ void returnsInstanceOfAbstractClassUsingFactoryMethod() throws NoSuchMethodExcep
 
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), noContext());
 
-        assertThat(actual).isInstanceOf(Charset.class);
+        assertThat(actual.getValue()).isInstanceOf(Charset.class);
     }
 
     @Test
@@ -67,9 +67,9 @@ void createOptionalWithArgument() throws NoSuchMethodException {
 
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), noContext());
 
-        assertThat(actual).isInstanceOf(Optional.class);
-        assertThat(actual).isNotEmpty();
-        assertThat(actual.get()).isInstanceOf(String.class);
+        assertThat(actual.getValue()).isInstanceOf(Optional.class);
+        assertThat(actual.getValue()).isNotEmpty();
+        assertThat(actual.getValue().get()).isInstanceOf(String.class);
     }
 
     @Test
@@ -79,8 +79,8 @@ void createOptionalWithoutArgument() throws NoSuchMethodException {
 
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), noContext());
 
-        assertThat(actual).isInstanceOf(Optional.class);
-        assertThat(actual).isEmpty();
+        assertThat(actual.getValue()).isInstanceOf(Optional.class);
+        assertThat(actual.getValue()).isEmpty();
     }
 
     @Test
@@ -90,7 +90,7 @@ void genericNoArgumentFactoryMethod() throws NoSuchMethodException {
 
         var actual = sut.invoke(new SpecimenFactory(new Context(Configuration.configure())), noContext());
 
-        assertThat(actual).isNotNull();
-        assertThat(actual.getValue()).isEqualTo(42);
+        assertThat(actual.getValue()).isNotNull();
+        assertThat(actual.getValue().getValue()).isEqualTo(42);
     }
 }