Use first line number from LineNumberTable for JavaCodeUnit's sourceC…

…odeLocation #344

So far, the `sourceCodeLocation` of `JavaMember`s does not contain a line number, as it cannot reliably be inferred from the byte code (cf. #75).

However, if the class file contains a [`LineNumberTable`](https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.7.12) for a method, using the smallest line number from the `LineNumberTable` for the member's `sourceCodeLocation` – even if this probably corresponds to the first executable statement and not to the method header definition – seems to be more useful to me than using the fallback line number `0` in any case.

So for example, I would infer the line number `10` from the following byte code:
```
  void methodWithBodyStartingInLine10();
    descriptor: ()V
    flags: (0x0000)
    Code:
      stack=2, locals=1, args_size=1
         0: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream;
         3: bipush        10
         5: invokevirtual #3                  // Method java/io/PrintStream.println:(I)V
         8: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream;
        11: bipush        11
        13: invokevirtual #3                  // Method java/io/PrintStream.println:(I)V
        16: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream;
        19: bipush        12
        21: invokevirtual #3                  // Method java/io/PrintStream.println:(I)V
        24: return
      LineNumberTable:
        line 10: 0
        line 11: 8
        line 12: 16
        line 13: 24
```
(My example's method header is actually defined in line 9, but I prefer 10 as opposed to 0... 😉)

Note that I do even get a line number for an empty method from the following byte code:
```
  void emptyMethodDefinedInLine15();
    descriptor: ()V
    flags: (0x0000)
    Code:
      stack=0, locals=1, args_size=1
         0: return
      LineNumberTable:
        line 15: 0
```

Even if line numbers inferred in this way do not exactly point to the method header definition, they can be used to  compare different methods (i.e., the ordering should be correct). This would allow for new rules like, for example (irrespective of whether I'd personally want to have them as arch rules or not):
* Public methods are defined _before_ private methods.
* `equals`, `hashCode` and `toString` are not generated by a framework (or a developer... 🙈) in the _same_ line (cf. #337)

With this pull request, line numbers are recorded for `JavaCodeUnit`s (`JavaMethod`s, `JavaConstructor`s, `JavaStaticInitializer`s) if the class file has a `LineNumberTable`.
(The reported line number `0` for `JavaField`s is unchanged, as it cannot be inferred from byte code.)

archunit-integration-test/src/test/java/com/tngtech/archunit/integration/ExamplesIntegrationTest.java

@@ -911,8 +911,8 @@ Stream<DynamicTest> MethodsTest() {
 
                 .ofRule("no code units that are declared in classes that reside in a package '..persistence..' "
                         + "should be annotated with @" + Secured.class.getSimpleName())
-                .by(ExpectedConstructor.of(SomeJpa.class).beingAnnotatedWith(Secured.class))
-                .by(ExpectedMethod.of(OtherJpa.class, "getEntityManager").beingAnnotatedWith(Secured.class))
+                .by(ExpectedConstructor.of(SomeJpa.class).inLine(15).beingAnnotatedWith(Secured.class))
+                .by(ExpectedMethod.of(OtherJpa.class, "getEntityManager").inLine(31).beingAnnotatedWith(Secured.class))
 
                 .toDynamicTests();
     }

archunit-integration-test/src/test/java/com/tngtech/archunit/testutils/ExpectedConstructor.java

@@ -15,17 +15,23 @@ public static ExpectedConstructor.Creator of(Class<?> owner, Class<?>... params)
     public static class Creator {
         private final Class<?> clazz;
         private final Class<?>[] params;
+        private int lineNumber;
 
         private Creator(Class<?> clazz, Class<?>[] params) {
             this.clazz = clazz;
             this.params = params;
         }
 
+        public  Creator inLine(int lineNumber) {
+            this.lineNumber = lineNumber;
+            return this;
+        }
+
         public ExpectedMessage beingAnnotatedWith(Class<? extends Annotation> annotationType) {
-            return new ExpectedMessage(String.format("Constructor <%s> is annotated with @%s in (%s.java:0)",
+            return new ExpectedMessage(String.format("Constructor <%s> is annotated with @%s in (%s.java:%d)",
                     formatMethod(clazz.getName(), JavaConstructor.CONSTRUCTOR_NAME, JavaClass.namesOf(params)),
                     annotationType.getSimpleName(),
-                    clazz.getSimpleName()));
+                    clazz.getSimpleName(), lineNumber));
         }
     }
 }

archunit-integration-test/src/test/java/com/tngtech/archunit/testutils/ExpectedMethod.java

@@ -16,13 +16,19 @@ public static class Creator {
         private final Class<?> clazz;
         private final String methodName;
         private final Class<?>[] params;
+        private int lineNumber;
 
         private Creator(Class<?> clazz, String methodName, Class<?>[] params) {
             this.clazz = clazz;
             this.methodName = methodName;
             this.params = params;
         }
 
+        public Creator inLine(int lineNumber) {
+            this.lineNumber = lineNumber;
+            return this;
+        }
+
         public ExpectedMessage toNotHaveRawReturnType(Class<?> type) {
             return method("does not have raw return type " + type.getName());
         }
@@ -37,7 +43,7 @@ public ExpectedMessage beingAnnotatedWith(Class<? extends Annotation> annotation
 
         private ExpectedMessage method(String message) {
             String methodDescription = format("Method <%s>", formatMethod(clazz.getName(), methodName, JavaClass.namesOf(params)));
-            String sourceCodeLocation = format("(%s.java:0)", clazz.getSimpleName());
+            String sourceCodeLocation = format("(%s.java:%d)", clazz.getSimpleName(), lineNumber);
             return new ExpectedMessage(format("%s %s in %s", methodDescription, message, sourceCodeLocation));
         }
     }

archunit/src/main/java/com/tngtech/archunit/core/domain/JavaMember.java

@@ -25,7 +25,6 @@
 import com.tngtech.archunit.Internal;
 import com.tngtech.archunit.PublicAPI;
 import com.tngtech.archunit.base.DescribedPredicate;
-import com.tngtech.archunit.base.HasDescription;
 import com.tngtech.archunit.base.Optional;
 import com.tngtech.archunit.core.domain.properties.CanBeAnnotated;
 import com.tngtech.archunit.core.domain.properties.HasAnnotations;
@@ -59,7 +58,7 @@ public abstract class JavaMember implements
         this.descriptor = checkNotNull(builder.getDescriptor());
         this.annotations = builder.getAnnotations(this);
         this.owner = checkNotNull(builder.getOwner());
-        this.sourceCodeLocation = SourceCodeLocation.of(owner);
+        this.sourceCodeLocation = SourceCodeLocation.of(owner, builder.getFirstLineNumber());
         this.modifiers = checkNotNull(builder.getModifiers());
     }
 

archunit/src/main/java/com/tngtech/archunit/core/importer/DomainBuilders.java

@@ -118,6 +118,7 @@ public abstract static class JavaMemberBuilder<OUTPUT, SELF extends JavaMemberBu
         private Set<JavaModifier> modifiers;
         private JavaClass owner;
         private ClassesByTypeName importedClasses;
+        private int firstLineNumber;
 
         private JavaMemberBuilder() {
         }
@@ -142,6 +143,10 @@ SELF withModifiers(Set<JavaModifier> modifiers) {
             return self();
         }
 
+        void recordLineNumber(int lineNumber) {
+            this.firstLineNumber = this.firstLineNumber == 0 ? lineNumber : Math.min(this.firstLineNumber, lineNumber);
+        }
+
         @SuppressWarnings("unchecked")
         SELF self() {
             return (SELF) this;
@@ -178,6 +183,10 @@ public JavaClass getOwner() {
             return owner;
         }
 
+        public int getFirstLineNumber() {
+            return firstLineNumber;
+        }
+
         @Override
         public final OUTPUT build(JavaClass owner, ClassesByTypeName importedClasses) {
             this.owner = owner;

archunit/src/main/java/com/tngtech/archunit/core/importer/JavaClassProcessor.java

@@ -320,6 +320,7 @@ public void visitCode() {
         @Override
         public void visitLineNumber(int line, Label start) {
             LOG.trace("Examining line number {}", line);
+            codeUnitBuilder.recordLineNumber(line);
             actualLineNumber = line;
             accessHandler.setLineNumber(actualLineNumber);
         }

archunit/src/test/java/com/tngtech/archunit/core/importer/ClassFileImporterTest.java

@@ -156,6 +156,7 @@
 import com.tngtech.archunit.core.importer.testexamples.integration.ClassD;
 import com.tngtech.archunit.core.importer.testexamples.integration.ClassXDependingOnClassesABCD;
 import com.tngtech.archunit.core.importer.testexamples.integration.InterfaceOfClassX;
+import com.tngtech.archunit.core.importer.testexamples.methodimport.ClassWithMultipleMethods;
 import com.tngtech.archunit.core.importer.testexamples.methodimport.ClassWithObjectVoidAndIntIntSerializableMethod;
 import com.tngtech.archunit.core.importer.testexamples.methodimport.ClassWithStringStringMethod;
 import com.tngtech.archunit.core.importer.testexamples.methodimport.ClassWithThrowingMethod;
@@ -739,6 +740,36 @@ public void imports_methods_with_correct_throws_declarations() throws Exception
         assertThat(method.getExceptionTypes()).matches(FirstCheckedException.class, SecondCheckedException.class);
     }
 
+    @Test
+    public void imports_members_with_sourceCodeLocation() throws Exception {
+        ImportedClasses importedClasses = classesIn("testexamples/methodimport");
+        String sourceFileName = "ClassWithMultipleMethods.java";
+
+        JavaClass javaClass = importedClasses.get(ClassWithMultipleMethods.class);
+        assertThat(javaClass.getField("usage").getSourceCodeLocation())
+                .hasToString("(" + sourceFileName + ":0)");  // the byte code has no line number associated with a field
+        assertThat(javaClass.getConstructor().getSourceCodeLocation())
+                .hasToString("(" + sourceFileName + ":3)");  // auto-generated constructor seems to get line of class definition
+        assertThat(javaClass.getStaticInitializer().get().getSourceCodeLocation())
+                .hasToString("(" + sourceFileName + ":5)");  // auto-generated static initializer seems to get line of first static variable definition
+        assertThat(javaClass.getMethod("methodDefinedInLine7").getSourceCodeLocation())
+                .hasToString("(" + sourceFileName + ":7)");
+        assertThat(javaClass.getMethod("methodWithBodyStartingInLine10").getSourceCodeLocation())
+                .hasToString("(" + sourceFileName + ":10)");
+        assertThat(javaClass.getMethod("emptyMethodDefinedInLine15").getSourceCodeLocation())
+                .hasToString("(" + sourceFileName + ":15)");
+        assertThat(javaClass.getMethod("emptyMethodEndingInLine19").getSourceCodeLocation())
+                .hasToString("(" + sourceFileName + ":19)");
+
+        javaClass = importedClasses.get(ClassWithMultipleMethods.InnerClass.class);
+        assertThat(javaClass.getMethod("methodWithBodyStartingInLine24").getSourceCodeLocation())
+                .hasToString("(" + sourceFileName + ":24)");
+
+        javaClass = importedClasses.get(ClassWithMultipleMethods.InnerClass.class.getName() + "$1");
+        assertThat(javaClass.getMethod("run").getSourceCodeLocation())
+                .hasToString("(" + sourceFileName + ":27)");
+    }
+
     @Test
     public void imports_methods_with_one_annotation_correctly() throws Exception {
         JavaClass clazz = classesIn("testexamples/annotationmethodimport").get(ClassWithAnnotatedMethods.class);

archunit/src/test/java/com/tngtech/archunit/core/importer/testexamples/methodimport/ClassWithMultipleMethods.java

@@ -0,0 +1,32 @@
+package com.tngtech.archunit.core.importer.testexamples.methodimport;
+
+public class ClassWithMultipleMethods {
+
+    static String usage = "ClassFileImporterTest's @Test imports_methods_with_correct_sourceCodeLocation";
+
+    int methodDefinedInLine7() { return 7; }
+
+    void methodWithBodyStartingInLine10() {
+        System.out.println(10);
+        System.out.println(11);
+        System.out.println(12);
+    }
+
+    void emptyMethodDefinedInLine15() { }
+
+    void emptyMethodEndingInLine19() {
+
+    }
+
+    public static class InnerClass {
+
+        void methodWithBodyStartingInLine24() {
+            new Runnable() {
+                @Override
+                public void run() {
+                    System.out.println(27);
+                }
+            };
+        }
+    }
+}

archunit/src/test/java/com/tngtech/archunit/lang/syntax/elements/GivenClassShouldTest.java

@@ -758,8 +758,8 @@ public void classes_should_have_only_private_constructor(ArchRule rule) {
         assertThat(rule).checking(importClasses(ClassWithPrivateConstructors.class))
                 .hasNoViolation();
         assertThat(rule).checking(importClasses(ClassWithPublicAndPrivateConstructor.class))
-                .hasOnlyViolations(String.format("Constructor <%s.<init>(%s)> is not private in (%s.java:0)",
-                        ClassWithPublicAndPrivateConstructor.class.getName(), String.class.getName(), getClass().getSimpleName()));
+                .hasOnlyViolations(String.format("Constructor <%s.<init>(%s)> is not private in (%s.java:%d)",
+                        ClassWithPublicAndPrivateConstructor.class.getName(), String.class.getName(), getClass().getSimpleName(), 1538));
     }
 
     @DataProvider

archunit/src/test/java/com/tngtech/archunit/lang/syntax/elements/MembersShouldConjunctionTest.java

@@ -44,11 +44,11 @@ public void orShould_ORs_conditions(ArchRule rule) {
                         RightOne.class.getName(), RightTwo.class.getName()));
         assertThat(report.getDetails()).containsOnly(
                 String.format("%s and %s",
-                        isNotDeclaredInMessage(WrongOne.class, CONSTRUCTOR_NAME, RightOne.class),
-                        isNotDeclaredInMessage(WrongOne.class, CONSTRUCTOR_NAME, RightTwo.class)),
+                        isNotDeclaredInMessage(WrongOne.class, CONSTRUCTOR_NAME, RightOne.class, 111),
+                        isNotDeclaredInMessage(WrongOne.class, CONSTRUCTOR_NAME, RightTwo.class, 111)),
                 String.format("%s and %s",
-                        isNotDeclaredInMessage(WrongOne.class, "wrongMethod1", RightOne.class),
-                        isNotDeclaredInMessage(WrongOne.class, "wrongMethod1", RightTwo.class)));
+                        isNotDeclaredInMessage(WrongOne.class, "wrongMethod1", RightOne.class, 113),
+                        isNotDeclaredInMessage(WrongOne.class, "wrongMethod1", RightTwo.class, 113)));
     }
 
     @DataProvider
@@ -75,24 +75,24 @@ public void andShould_ANDs_conditions(ArchRule rule) {
                         "members should not be declared in %s and should not be declared in %s",
                         WrongOne.class.getName(), WrongTwo.class.getName()));
         assertThat(report.getDetails()).containsOnly(
-                isDeclaredInMessage(WrongOne.class, CONSTRUCTOR_NAME),
-                isDeclaredInMessage(WrongOne.class, "wrongMethod1"),
-                isDeclaredInMessage(WrongTwo.class, CONSTRUCTOR_NAME),
-                isDeclaredInMessage(WrongTwo.class, "wrongMethod2"));
+                isDeclaredInMessage(WrongOne.class, CONSTRUCTOR_NAME, 111),
+                isDeclaredInMessage(WrongOne.class, "wrongMethod1", 113),
+                isDeclaredInMessage(WrongTwo.class, CONSTRUCTOR_NAME, 117),
+                isDeclaredInMessage(WrongTwo.class, "wrongMethod2", 119));
     }
 
-    private String isDeclaredInMessage(Class<?> clazz, String methodName) {
-        return message(clazz, methodName, "", clazz);
+    private String isDeclaredInMessage(Class<?> clazz, String methodName, int lineNumber) {
+        return message(clazz, methodName, "", clazz, lineNumber);
     }
 
-    private String isNotDeclaredInMessage(Class<?> clazz, String methodName, Class<?> expectedTarget) {
-        return message(clazz, methodName, "not ", expectedTarget);
+    private String isNotDeclaredInMessage(Class<?> clazz, String methodName, Class<?> expectedTarget, int lineNumber) {
+        return message(clazz, methodName, "not ", expectedTarget, lineNumber);
     }
 
-    private String message(Class<?> clazz, String methodName, String optionalNot, Class<?> expectedTarget) {
-        return String.format("%s <%s.%s()> is %sdeclared in %s in (%s.java:0)",
+    private String message(Class<?> clazz, String methodName, String optionalNot, Class<?> expectedTarget, int lineNumber) {
+        return String.format("%s <%s.%s()> is %sdeclared in %s in (%s.java:%d)",
                 CONSTRUCTOR_NAME.equals(methodName) ? "Constructor" : "Method",
-                clazz.getName(), methodName, optionalNot, expectedTarget.getName(), getClass().getSimpleName());
+                clazz.getName(), methodName, optionalNot, expectedTarget.getName(), getClass().getSimpleName(), lineNumber);
     }
 
     @SuppressWarnings("unused")