Add FilePosition to ClassSource, if possible. Closes #196 (#197)

This change tries to parse the Test Source file and add the Position of
the Assertion Field to the ClassSource. To locate the source file, this
makes some assumptions about the direcory structure and it may not work
with non-standard directory names and/or trees.

confidence-core/src/main/java/org/saynotobugs/confidence/utils/FailSafe.java

@@ -25,7 +25,7 @@
 /**
  * A {@link ThrowingFunction} to {@link Function} adapter that always returns a result, even in case a {@link Throwable} was thrown.
  */
-public final class FailSafe<Argument, Result> implements Function<Argument, Result>
+public final class FailSafe<Argument, Result> implements Function<Argument, Result>, java.util.function.Function<Argument, Result>
 {
     private final ThrowingFunction<Argument, Result> delegate;
     private final Function<Throwable, Result> fallback;
@@ -52,4 +52,10 @@ public Result value(Argument argument)
             return fallback.value(e);
         }
     }
+
+    @Override
+    public Result apply(Argument argument)
+    {
+        return value(argument);
+    }
 }

confidence-core/src/test/java/org/saynotobugs/confidence/utils/FailSafeTest.java

@@ -23,6 +23,8 @@
 import org.saynotobugs.confidence.quality.object.EqualTo;
 
 import static org.saynotobugs.confidence.Assertion.assertThat;
+import static org.saynotobugs.confidence.core.quality.Function.maps;
+import static org.saynotobugs.confidence.core.quality.Grammar.to;
 
 
 class FailSafeTest
@@ -43,4 +45,21 @@ void testException()
             }),
             new Has<>(fs -> fs.value("123"), new EqualTo<>("xyz")));
     }
+
+    @Test
+    void testJavaFunctionNoException()
+    {
+        assertThat(new FailSafe<String, String>(t -> "fail", x -> x),
+            maps("123", to("123")));
+    }
+
+
+    @Test
+    void testJavaFunctionException()
+    {
+        assertThat(new FailSafe<String, String>(Throwable::getMessage, x -> {
+                throw new IllegalArgumentException("xyz");
+            }),
+            maps("123", to("xyz")));
+    }
 }

confidence-incubator/build.gradle

@@ -35,6 +35,7 @@ dependencies {
     implementation libs.junit.jupiter.engine
     implementation project(':confidence-core')
     implementation libs.jems2.confidence
+    implementation 'com.github.javaparser:javaparser-core:3.26.1'
 
     testImplementation project(':confidence-test')
     testImplementation libs.jems2.testing

confidence-incubator/src/main/java/org/saynotobugs/confidence/junit5/engine/testengine/testdescriptor/ClassTestDescriptor.java

@@ -18,6 +18,8 @@
 
 package org.saynotobugs.confidence.junit5.engine.testengine.testdescriptor;
 
+import com.github.javaparser.JavaParser;
+import com.github.javaparser.ast.CompilationUnit;
 import org.junit.platform.engine.EngineExecutionListener;
 import org.junit.platform.engine.TestDescriptor;
 import org.junit.platform.engine.TestExecutionResult;
@@ -26,8 +28,16 @@
 import org.junit.platform.engine.support.descriptor.ClassSource;
 import org.saynotobugs.confidence.junit5.engine.Assertion;
 import org.saynotobugs.confidence.junit5.engine.testengine.Testable;
+import org.saynotobugs.confidence.utils.FailSafe;
 
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.security.CodeSource;
 import java.util.Arrays;
+import java.util.Optional;
+
+import static java.util.Optional.empty;
+import static java.util.Optional.ofNullable;
 
 
 /**
@@ -43,7 +53,7 @@ public ClassTestDescriptor(UniqueId uniqueId, Class<?> javaClass)
 
         Arrays.stream(javaClass.getDeclaredFields())
             .filter(field -> Assertion.class.isAssignableFrom(field.getType()))
-            .map(field -> new FieldTestDescriptor(getUniqueId(), javaClass, field))
+            .map(field -> new FieldTestDescriptor(getUniqueId(), javaClass, testSources(javaClass), field))
             .forEach(this::addChild);
     }
 
@@ -73,4 +83,37 @@ public Type getType()
     {
         return Type.CONTAINER;
     }
+
+
+    private static Optional<CompilationUnit> testSources(Class<?> clazz)
+    {
+        return gradleTestSourcePath(clazz)
+            .or(() -> naiveTestSourcePath(clazz))
+            .flatMap(new FailSafe<>(any -> empty(), path -> new JavaParser().parse(path).getResult()));
+    }
+
+    private static Optional<Path> naiveTestSourcePath(Class<?> testClazz)
+    {
+        return Optional.of(Path.of("src", "main")
+                .resolve(Path.of("java", testClazz.getPackage().getName().split("\\.")))
+                .resolve(testClazz.getSimpleName() + ".java"))
+            .filter(Files::isRegularFile);
+    }
+
+    private static Optional<Path> gradleTestSourcePath(Class<?> testClazz)
+    {
+        return ofNullable(System.getProperty("user.dir"))
+            .map(Path::of)
+            .flatMap(workingDir ->
+                Optional.ofNullable(testClazz.getProtectionDomain().getCodeSource())
+                    .map(CodeSource::getLocation)
+                    .flatMap(new FailSafe<>(any -> empty(), url -> Optional.of(url.toURI())))
+                    .map(source -> workingDir.relativize(Path.of(source)))
+                    .map(relativeClassPath ->
+                        workingDir.resolve(Path.of("src", relativeClassPath.getName(3).toString())
+                            .resolve(Path.of(relativeClassPath.getName(2).toString(), testClazz.getPackageName().split("\\.")))
+                            .resolve(testClazz.getSimpleName() + ".java")))
+                    .filter(Files::isRegularFile));
+    }
+
 }

confidence-incubator/src/main/java/org/saynotobugs/confidence/junit5/engine/testengine/testdescriptor/FieldTestDescriptor.java

@@ -18,17 +18,21 @@
 
 package org.saynotobugs.confidence.junit5.engine.testengine.testdescriptor;
 
+import com.github.javaparser.ast.CompilationUnit;
+import com.github.javaparser.ast.body.FieldDeclaration;
 import org.junit.platform.engine.EngineExecutionListener;
 import org.junit.platform.engine.TestDescriptor;
 import org.junit.platform.engine.UniqueId;
 import org.junit.platform.engine.support.descriptor.AbstractTestDescriptor;
 import org.junit.platform.engine.support.descriptor.ClassSource;
+import org.junit.platform.engine.support.descriptor.FilePosition;
 import org.saynotobugs.confidence.junit5.engine.Assertion;
 import org.saynotobugs.confidence.junit5.engine.testengine.Testable;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
+import java.util.Optional;
 
 
 /**
@@ -40,11 +44,11 @@ public final class FieldTestDescriptor extends AbstractTestDescriptor implements
     private final Field javaField;
 
 
-    public FieldTestDescriptor(UniqueId uniqueId, Class<?> javaClass, Field javaField)
+    public FieldTestDescriptor(UniqueId uniqueId, Class<?> javaClass, Optional<CompilationUnit> testSource, Field javaField)
     {
         super(uniqueId.append("field", javaField.getName()),
             (javaField.getName().replace("_", " ")).trim(),
-            ClassSource.from(javaClass));
+            ClassSource.from(javaClass, getFieldLineNumber(testSource, javaField.getName())));
         this.javaClass = javaClass;
         this.javaField = javaField;
     }
@@ -73,4 +77,16 @@ public Type getType()
     {
         return Type.TEST;
     }
+
+
+    private static FilePosition getFieldLineNumber(Optional<CompilationUnit> compilationUnit, String fieldName)
+    {
+        return compilationUnit.flatMap(cu -> cu.findAll(FieldDeclaration.class)
+                .stream().flatMap(fieldDeclaration -> fieldDeclaration.getVariables().stream())
+                .filter(node -> fieldName.equals(node.getName().asString()))
+                .flatMap(node -> node.getBegin().stream())
+                .map(begin -> FilePosition.from(begin.line, begin.column))
+                .findFirst())
+            .orElse(null);
+    }
 }