fix: some methods were not checking for valid keys

This is now fixed and tests are added for those situations.

Author: quintesse

src/main/java/org/codejive/properties/Properties.java

@@ -426,10 +426,15 @@ private Cursor addNewKeyValue(String rawKey, String key, String rawValue, String
     @Override
     public String remove(Object key) {
         String skey = key.toString();
-        removeItem(skey);
-        return values.remove(skey);
+        if (containsKey(key)) {
+            removeItem(skey);
+            return values.remove(skey);
+        } else {
+            return null;
+        }
     }
 
+    // Calling code MUST make sure skey exists!
     private void removeItem(String skey) {
         setComment(skey, Collections.emptyList());
         Cursor pos = indexOf(skey);
@@ -580,7 +585,11 @@ private String getPrefix(String comment) {
 
     private List<Integer> findPropertyCommentLines(String key) {
         Cursor pos = indexOf(key);
-        return findPropertyCommentLines(pos);
+        if (pos.hasToken()) {
+            return findPropertyCommentLines(pos);
+        } else {
+            return Collections.emptyList();
+        }
     }
 
     /**

src/test/java/org/codejive/properties/TestProperties.java

@@ -10,6 +10,7 @@
 import java.util.AbstractMap;
 import java.util.Collections;
 import java.util.Iterator;
+import java.util.NoSuchElementException;
 import org.junit.jupiter.api.Test;
 
 public class TestProperties {
@@ -197,6 +198,24 @@ void testGetRaw() throws IOException, URISyntaxException {
         assertThat(p.getRaw("key.4")).isEqualTo("\\u1234\u1234");
     }
 
+    @Test
+    void testGetNonExistent() throws IOException, URISyntaxException {
+        Properties p = Properties.loadProperties(getResource("/test.properties"));
+        assertThat(p.get("wrong")).isNull();
+    }
+
+    @Test
+    void testGetPropertyNonExistent() throws IOException, URISyntaxException {
+        Properties p = Properties.loadProperties(getResource("/test.properties"));
+        assertThat(p.getProperty("wrong")).isNull();
+    }
+
+    @Test
+    void testGetPropertyDefault() throws IOException, URISyntaxException {
+        Properties p = Properties.loadProperties(getResource("/test.properties"));
+        assertThat(p.getProperty("wrong", "right")).isEqualTo("right");
+    }
+
     @Test
     void testGetComment() throws IOException, URISyntaxException {
         Properties p = Properties.loadProperties(getResource("/test.properties"));
@@ -206,13 +225,20 @@ void testGetComment() throws IOException, URISyntaxException {
                 .containsExactly("# another comment", "! and a comment", "! block");
     }
 
+    @Test
+    void testGetCommentNonExistent() throws IOException, URISyntaxException {
+        Properties p = Properties.loadProperties(getResource("/test.properties"));
+        assertThat(p.getComment("wrong")).isEmpty();
+    }
+
     @Test
     void testCommentFirstLine() throws IOException, URISyntaxException {
         Properties p = Properties.loadProperties(getResource("/test-commentfirstline.properties"));
         assertThat(p.getComment("one")).containsExactly("#comment1", "#  comment2");
         StringWriter sw = new StringWriter();
         p.store(sw);
-        assertThat(sw.toString()).isEqualTo(readAll(getResource("/test-commentfirstline.properties")));
+        assertThat(sw.toString())
+                .isEqualTo(readAll(getResource("/test-commentfirstline.properties")));
     }
 
     @Test
@@ -229,6 +255,16 @@ void testSetComment() throws IOException, URISyntaxException {
         assertThat(sw.toString()).isEqualTo(readAll(getResource("/test-comment.properties")));
     }
 
+    @Test
+    void testSetCommentNonExistent() throws IOException, URISyntaxException {
+        Properties p = Properties.loadProperties(getResource("/test.properties"));
+        assertThatThrownBy(
+                        () -> {
+                            p.setComment("wrong", "dummy");
+                        })
+                .isInstanceOf(NoSuchElementException.class);
+    }
+
     @Test
     void testPut() throws IOException, URISyntaxException {
         Properties p = new Properties();
@@ -499,6 +535,12 @@ void testRemoveAll() throws IOException, URISyntaxException {
         assertThat(sw.toString()).isEqualTo(readAll(getResource("/test-removeall.properties")));
     }
 
+    @Test
+    void testRemoveNonExistent() throws IOException, URISyntaxException {
+        Properties p = Properties.loadProperties(getResource("/test.properties"));
+        assertThat(p.remove("wrong")).isNull();
+    }
+
     @Test
     void testRemoveMiddleIterator() throws IOException, URISyntaxException {
         Properties p = Properties.loadProperties(getResource("/test.properties"));