Add unit and integration tests

pom.xml

@@ -29,6 +29,12 @@
             <artifactId>jdom</artifactId>
             <version>1.1.3</version>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.10.2</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>

src/test/java/com/bytehamster/androidxmlformatter/IntegrationTest.java

@@ -0,0 +1,298 @@
+package com.bytehamster.androidxmlformatter;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.jdom.Document;
+import org.jdom.input.SAXBuilder;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.io.ByteArrayOutputStream;
+import java.io.InputStream;
+import java.io.StringWriter;
+import java.nio.charset.StandardCharsets;
+
+/**
+ * Integration tests that verify XML formatting with various options by comparing input XML files
+ * against expected output XML files.
+ */
+class IntegrationTest {
+
+    private static final String INTEGRATION_DIR = "/integration/";
+    private static final String INPUT_SUFFIX = "_input.xml";
+    private static final String EXPECTED_SUFFIX = "_expected.xml";
+
+    private String loadResource(String path) throws Exception {
+        try (InputStream is = getClass().getResourceAsStream(path)) {
+            if (is == null) {
+                throw new IllegalArgumentException("Resource not found: " + path);
+            }
+            ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+            int bytesRead;
+            byte[] data = new byte[1024];
+            while ((bytesRead = is.read(data, 0, data.length)) != -1) {
+                buffer.write(data, 0, bytesRead);
+            }
+            return new String(buffer.toByteArray(), StandardCharsets.UTF_8);
+        }
+    }
+
+    private Document parseResource(String path) throws Exception {
+        try (InputStream is = getClass().getResourceAsStream(path)) {
+            if (is == null) {
+                throw new IllegalArgumentException("Resource not found: " + path);
+            }
+            return new SAXBuilder().build(is);
+        }
+    }
+
+    private String formatDocument(AndroidXmlOutputter outputter, Document doc) throws Exception {
+        StringWriter writer = new StringWriter();
+        outputter.output(doc, writer);
+        return writer.toString();
+    }
+
+    private void assertFormattedOutputMatches(
+            String testName,
+            int indention,
+            int attributeIndention,
+            String[] namespaceOrder,
+            String[] attributeOrder,
+            boolean attributeSort,
+            boolean namespaceSort)
+            throws Exception {
+
+        Document inputDoc = parseResource(INTEGRATION_DIR + testName + INPUT_SUFFIX);
+        String expected = loadResource(INTEGRATION_DIR + testName + EXPECTED_SUFFIX);
+
+        AndroidXmlOutputter outputter = new AndroidXmlOutputter(
+                indention,
+                attributeIndention,
+                namespaceOrder,
+                attributeOrder,
+                attributeSort,
+                namespaceSort);
+
+        String actual = formatDocument(outputter, inputDoc);
+
+        // Normalize line endings for comparison
+        expected = expected.replace("\r\n", "\n").trim();
+        actual = actual.replace("\r\n", "\n").trim();
+
+        assertEquals(expected, actual, "Formatted output should match expected for: " + testName);
+    }
+
+    // === Default Options Test ===
+
+    @Test
+    @DisplayName("Default options: id, layout_width, layout_height first with 4-space indentation")
+    void testDefaultOptions() throws Exception {
+        assertFormattedOutputMatches(
+                "default_options",
+                4, // indention
+                4, // attribute indention
+                new String[] { "android" }, // namespace order
+                new String[] { "id", "layout_width", "layout_height" }, // attribute order
+                false, // attribute sort
+                false // namespace sort
+        );
+    }
+
+    // === Custom Indentation Test ===
+
+    @Test
+    @DisplayName("Custom indentation: 2 spaces instead of 4")
+    void testCustomIndention() throws Exception {
+        assertFormattedOutputMatches(
+                "custom_indention",
+                2, // indention
+                2, // attribute indention
+                new String[] { "android" }, // namespace order
+                new String[] { "id", "layout_width", "layout_height" }, // attribute order
+                false, // attribute sort
+                false // namespace sort
+        );
+    }
+
+    // === Custom Attribute Indentation Test ===
+
+    @Test
+    @DisplayName("Custom attribute indentation: 8 spaces for attributes")
+    void testCustomAttributeIndention() throws Exception {
+        assertFormattedOutputMatches(
+                "custom_attribute_indention",
+                4, // indention
+                8, // attribute indention
+                new String[] { "android" }, // namespace order
+                new String[] { "id", "layout_width", "layout_height" }, // attribute order
+                false, // attribute sort
+                false // namespace sort
+        );
+    }
+
+    // === Custom Attribute Order Test ===
+
+    @Test
+    @DisplayName("Custom attribute order: text, background first")
+    void testCustomAttributeOrder() throws Exception {
+        assertFormattedOutputMatches(
+                "custom_attribute_order",
+                4, // indention
+                4, // attribute indention
+                new String[] { "android" }, // namespace order
+                new String[] { "text", "background" }, // attribute order
+                false, // attribute sort
+                false // namespace sort
+        );
+    }
+
+    // === Alphabetical Attribute Sort Test ===
+
+    @Test
+    @DisplayName("Attribute sort: alphabetical ordering of attributes")
+    void testAttributeSort() throws Exception {
+        assertFormattedOutputMatches(
+                "attribute_sort",
+                4, // indention
+                4, // attribute indention
+                new String[] { "android" }, // namespace order
+                new String[] {}, // attribute order (empty for pure alphabetical)
+                true, // attribute sort
+                false // namespace sort
+        );
+    }
+
+    // === Custom Namespace Order Test ===
+
+    @Test
+    @DisplayName("Custom namespace order: tools, app, android")
+    void testCustomNamespaceOrder() throws Exception {
+        assertFormattedOutputMatches(
+                "custom_namespace_order",
+                4, // indention
+                4, // attribute indention
+                new String[] { "tools", "app", "android" }, // namespace order
+                new String[] { "id", "layout_width", "layout_height" }, // attribute order
+                false, // attribute sort
+                false // namespace sort
+        );
+    }
+
+    // === Alphabetical Namespace Sort Test ===
+
+    @Test
+    @DisplayName("Namespace sort: alphabetical ordering of namespaces")
+    void testNamespaceSort() throws Exception {
+        assertFormattedOutputMatches(
+                "namespace_sort",
+                4, // indention
+                4, // attribute indention
+                new String[] {}, // namespace order (empty for pure alphabetical)
+                new String[] { "id", "layout_width", "layout_height" }, // attribute order
+                false, // attribute sort
+                true // namespace sort
+        );
+    }
+
+    // === Combined Options Test ===
+
+    @Test
+    @DisplayName("Combined options: 2-space indent, 6-space attr indent, both sorts enabled")
+    void testCombinedOptions() throws Exception {
+        assertFormattedOutputMatches(
+                "combined_options",
+                2, // indention
+                6, // attribute indention
+                new String[] {}, // namespace order (empty for alphabetical)
+                new String[] {}, // attribute order (empty for alphabetical)
+                true, // attribute sort
+                true // namespace sort
+        );
+    }
+
+    // === Additional Integration Tests ===
+
+    @Test
+    @DisplayName("Zero indentation: no indentation for elements or attributes")
+    void testZeroIndentation() throws Exception {
+        Document inputDoc = parseResource(INTEGRATION_DIR + "default_options" + INPUT_SUFFIX);
+
+        AndroidXmlOutputter outputter = new AndroidXmlOutputter(
+                0,
+                0,
+                new String[] { "android" },
+                new String[] { "id", "layout_width", "layout_height" },
+                false,
+                false);
+
+        String result = formatDocument(outputter, inputDoc);
+
+        // With zero indentation, child elements should not be indented
+        assertTrue(result.contains("<Button"), "Should contain Button element");
+        assertTrue(result.contains("<TextView"), "Should contain TextView element");
+        assertFalse(
+                result.contains("\n    <Button"),
+                "Button should not be indented with 4 spaces when indentation is 0");
+    }
+
+    @Test
+    @DisplayName("Verify output is valid XML that can be parsed")
+    void testOutputIsValidXml() throws Exception {
+        Document inputDoc = parseResource(INTEGRATION_DIR + "default_options" + INPUT_SUFFIX);
+
+        AndroidXmlOutputter outputter = new AndroidXmlOutputter(
+                4,
+                4,
+                new String[] { "android" },
+                new String[] { "id", "layout_width", "layout_height" },
+                false,
+                false);
+
+        String result = formatDocument(outputter, inputDoc);
+
+        // Parse the output to verify it's valid XML
+        SAXBuilder builder = new SAXBuilder();
+        Document parsedDoc = builder.build(new java.io.StringReader(result));
+
+        assertNotNull(parsedDoc, "Output should be parseable as XML");
+        assertEquals(
+                "LinearLayout",
+                parsedDoc.getRootElement().getName(),
+                "Root element should be LinearLayout");
+    }
+
+    @Test
+    @DisplayName("Nested elements maintain correct structure")
+    void testNestedElementsStructure() throws Exception {
+        Document inputDoc = parseResource(INTEGRATION_DIR + "default_options" + INPUT_SUFFIX);
+
+        AndroidXmlOutputter outputter = new AndroidXmlOutputter(
+                4,
+                4,
+                new String[] { "android" },
+                new String[] { "id", "layout_width", "layout_height" },
+                false,
+                false);
+
+        String result = formatDocument(outputter, inputDoc);
+
+        // Verify nested structure
+        assertTrue(result.contains("<LinearLayout"), "Should contain LinearLayout");
+        assertTrue(result.contains("</LinearLayout>"), "Should have closing LinearLayout tag");
+        assertTrue(result.contains("<Button"), "Should contain Button");
+        assertTrue(result.contains("<TextView"), "Should contain TextView");
+
+        // Verify proper nesting (Button and TextView are inside LinearLayout)
+        int linearLayoutStart = result.indexOf("<LinearLayout");
+        int linearLayoutEnd = result.indexOf("</LinearLayout>");
+        int buttonPos = result.indexOf("<Button");
+        int textViewPos = result.indexOf("<TextView");
+
+        assertTrue(
+                buttonPos > linearLayoutStart && buttonPos < linearLayoutEnd,
+                "Button should be inside LinearLayout");
+        assertTrue(
+                textViewPos > linearLayoutStart && textViewPos < linearLayoutEnd,
+                "TextView should be inside LinearLayout");
+    }
+}

src/test/resources/integration/attribute_sort_expected.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<View
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:alpha="0.5"
+    android:background="#FFF"
+    android:elevation="4dp"
+    android:id="@+id/view"
+    android:zIndex="1" />

src/test/resources/integration/attribute_sort_input.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<View xmlns:android="http://schemas.android.com/apk/res/android"
+    android:zIndex="1"
+    android:alpha="0.5"
+    android:background="#FFF"
+    android:elevation="4dp"
+    android:id="@+id/view" />

src/test/resources/integration/combined_options_expected.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<View
+      xmlns:android="http://schemas.android.com/apk/res/android"
+      xmlns:app="http://schemas.android.com/apk/res-auto"
+      android:alpha="0.5"
+      android:id="@+id/view"
+      android:zIndex="1"
+      app:customA="a"
+      app:customZ="z" />

src/test/resources/integration/combined_options_input.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<View xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:zIndex="1"
+    android:alpha="0.5"
+    android:id="@+id/view"
+    app:customZ="z"
+    app:customA="a" />

src/test/resources/integration/custom_attribute_indention_expected.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Button
+        xmlns:android="http://schemas.android.com/apk/res/android"
+        android:id="@+id/btn"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Click" />

src/test/resources/integration/custom_attribute_indention_input.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Button xmlns:android="http://schemas.android.com/apk/res/android"
+    android:text="Click"
+    android:id="@+id/btn"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content" />

src/test/resources/integration/custom_attribute_order_expected.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Button
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:text="Click"
+    android:background="#FFFFFF"
+    android:id="@+id/btn"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content" />

src/test/resources/integration/custom_attribute_order_input.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Button xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/btn"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:text="Click"
+    android:background="#FFFFFF" />

src/test/resources/integration/custom_indention_expected.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout
+  xmlns:android="http://schemas.android.com/apk/res/android"
+  android:id="@+id/container"
+  android:layout_width="match_parent"
+  android:layout_height="match_parent">
+
+  <Button
+    android:id="@+id/btn"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:text="Test" />
+
+</LinearLayout>