Prevent NPE in tryCreateParentDirectories (#40)

* Prevent NPE in tryCreateParentDirectories

* Fix tryCreateParentDirectories test case

Author: tomwmth

configlib-yaml/src/main/java/de/exlll/configlib/YamlConfigurationStore.java

@@ -89,9 +89,9 @@ public void save(T configuration, Path configurationFile) {
         yamlFileWriter.writeYaml(dumpedYaml, extractedCommentNodes);
     }
 
-    private void tryCreateParentDirectories(Path configurationFile) {
+    void tryCreateParentDirectories(Path configurationFile) {
         Path parent = configurationFile.getParent();
-        if (!Files.exists(parent) && properties.createParentDirectories()) {
+        if (properties.createParentDirectories() && parent != null && !Files.exists(parent)) {
             try {
                 Files.createDirectories(parent);
             } catch (IOException e) {

configlib-yaml/src/test/java/de/exlll/configlib/YamlConfigurationStoreTest.java

@@ -557,4 +557,19 @@ void updateResolvesEnvVarsIfFileDoesOrDoesNotExist(boolean createFile) {
         assertThat(config.s, is("S2"));
         assertThat(config.i, is(10));
     }
+
+    @ParameterizedTest
+    @ValueSource(booleans = {true, false})
+    void tryCreateParentDirectoriesDoesNotThrowIfParentIsNull(boolean createParentDirectories) {
+        YamlConfigurationProperties properties = YamlConfigurationProperties.newBuilder()
+                .createParentDirectories(createParentDirectories)
+                .build();
+        YamlConfigurationStore<A> store = new YamlConfigurationStore<>(
+                A.class,
+                properties
+        );
+
+        Path path = fs.getPath("config.yml");
+        assertDoesNotThrow(() -> store.tryCreateParentDirectories(path));
+    }
 }