#1497 Show specific message for invalid YAML files (#1506)

* #1497 Throw dedicated exception for invalid YAML files and handle it on startup
- Wrap SnakeYAML exceptions when loading config.yml and commands.yml on startup into own exception type
- Handle exception type on startup with specific error message

* #1497 Fix inaccurate JavaDoc comment

src/test/java/fr/xephi/authme/service/yaml/YamlFileResourceProviderTest.java

@@ -0,0 +1,48 @@
+package fr.xephi.authme.service.yaml;
+
+import ch.jalu.configme.resource.YamlFileResource;
+import fr.xephi.authme.TestHelper;
+import org.junit.Test;
+import org.yaml.snakeyaml.parser.ParserException;
+
+import java.io.File;
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.instanceOf;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.fail;
+
+/**
+ * Test for {@link YamlFileResourceProvider}.
+ */
+public class YamlFileResourceProviderTest {
+
+    @Test
+    public void shouldLoadValidFile() {
+        // given
+        File yamlFile = TestHelper.getJarFile(TestHelper.PROJECT_ROOT + "service/yaml/validYaml.yml");
+
+        // when
+        YamlFileResource resource = YamlFileResourceProvider.loadFromFile(yamlFile);
+
+        // then
+        assertThat(resource.getString("test.jkl"), equalTo("Test test"));
+    }
+
+    @Test
+    public void shouldThrowForInvalidFile() {
+        // given
+        File yamlFile = TestHelper.getJarFile(TestHelper.PROJECT_ROOT + "service/yaml/invalidYaml.yml");
+
+        // when
+        try {
+            YamlFileResourceProvider.loadFromFile(yamlFile);
+
+            // then
+            fail("Expected exception to be thrown");
+        } catch (YamlParseException e) {
+            assertThat(e.getFile(), equalTo(yamlFile.getPath()));
+            assertThat(e.getCause(), instanceOf(ParserException.class));
+        }
+    }
+}

src/test/java/fr/xephi/authme/util/ExceptionUtilsTest.java

@@ -0,0 +1,54 @@
+package fr.xephi.authme.util;
+
+import fr.xephi.authme.ReflectionTestUtils;
+import org.junit.Test;
+
+import java.util.ConcurrentModificationException;
+
+import static org.hamcrest.Matchers.nullValue;
+import static org.hamcrest.Matchers.sameInstance;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test for {@link ExceptionUtils}.
+ */
+public class ExceptionUtilsTest {
+
+    @Test
+    public void shouldFindWantedThrowable() {
+        // given
+        ConcurrentModificationException initialCme = new ConcurrentModificationException();
+        Throwable th = new Throwable(initialCme);
+        ConcurrentModificationException cme = new ConcurrentModificationException(th);
+        IllegalStateException ise = new IllegalStateException(cme);
+        UnsupportedOperationException uoe = new UnsupportedOperationException(ise);
+        ReflectiveOperationException roe = new ReflectiveOperationException(uoe);
+
+        // when
+        IllegalStateException resultIse = ExceptionUtils.findThrowableInCause(IllegalStateException.class, roe);
+        ConcurrentModificationException resultCme = ExceptionUtils.findThrowableInCause(ConcurrentModificationException.class, cme);
+        StackOverflowError resultSoe = ExceptionUtils.findThrowableInCause(StackOverflowError.class, cme);
+
+        // then
+        assertThat(resultIse, sameInstance(ise));
+        assertThat(resultCme, sameInstance(cme));
+        assertThat(resultSoe, nullValue());
+    }
+
+    @Test
+    public void shouldHandleCircularCausesGracefully() {
+        // given
+        IllegalStateException ise = new IllegalStateException();
+        UnsupportedOperationException uoe = new UnsupportedOperationException(ise);
+        ReflectiveOperationException roe = new ReflectiveOperationException(uoe);
+        ReflectionTestUtils.setField(Throwable.class, ise, "cause", roe);
+
+        // when
+        NullPointerException resultNpe = ExceptionUtils.findThrowableInCause(NullPointerException.class, uoe);
+        UnsupportedOperationException resultUoe = ExceptionUtils.findThrowableInCause(UnsupportedOperationException.class, uoe);
+
+        // then
+        assertThat(resultNpe, nullValue());
+        assertThat(resultUoe, sameInstance(uoe));
+    }
+}

src/test/resources/fr/xephi/authme/service/yaml/invalidYaml.yml

@@ -0,0 +1,5 @@
+# File with invalid YAML
+test:
+  abc: 'test'
+  def: 'Going to forget a quote here
+  jkl: 'Test test'

src/test/resources/fr/xephi/authme/service/yaml/validYaml.yml

@@ -0,0 +1,4 @@
+test:
+  abc: 'test'
+  def: 'All quotes are good here'
+  jkl: 'Test test'