Add unit tests for applyTemplatePrefix in Init.java

Author: Hiteshsai007

impl/maven-cli/src/main/java/org/apache/maven/cling/invoker/mvnenc/goals/Init.java

@@ -144,13 +144,7 @@ public int doExecute(EncryptContext context) throws Exception {
                             throw new InterruptedException();
                         }
                         String result = editMap.get("edit").getResult();
-                        if (template.contains("$")) {
-                            String prefix = template.substring(0, template.indexOf('$'));
-                            if (!result.startsWith(prefix)) {
-                                result = prefix + result;
-                            }
-                        }
-                        final String finalResult = result;
+                        final String finalResult = applyTemplatePrefix(template, result);
                         dispatcherConfigResult.put(editable.getKey(), new PromptResultItemIF() {
                             @Override
                             public String getResult() {
@@ -289,4 +283,27 @@ private PromptBuilder configureDispatcher(
         }
         return promptBuilder;
     }
+
+    /**
+     * Applies the template prefix to the user input if needed.
+     * <p>
+     * When a template contains a {@code $} placeholder (e.g., {@code "env:$VARIABLE_NAME"}),
+     * the prefix before the {@code $} is extracted and prepended to the user's input
+     * if it's not already present. This ensures that the generated configuration always
+     * contains well-formed source values (e.g., {@code "env:MVN_PASSWORD"} instead of
+     * just {@code "MVN_PASSWORD"}).
+     *
+     * @param template the template string potentially containing a {@code $} placeholder
+     * @param userInput the user's raw input
+     * @return the user input with the template prefix applied if needed
+     */
+    static String applyTemplatePrefix(String template, String userInput) {
+        if (template.contains("$")) {
+            String prefix = template.substring(0, template.indexOf('$'));
+            if (!prefix.isEmpty() && !userInput.startsWith(prefix)) {
+                return prefix + userInput;
+            }
+        }
+        return userInput;
+    }
 }

impl/maven-cli/src/test/java/org/apache/maven/cling/invoker/mvnenc/goals/InitTest.java

@@ -0,0 +1,91 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.cling.invoker.mvnenc.goals;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * Tests for {@link Init}, specifically the prefix-prepending logic
+ * that ensures user input is correctly formatted with the template prefix
+ * (e.g., {@code "env:"}) when saving encryption configuration.
+ */
+class InitTest {
+
+    @Test
+    void applyTemplatePrefixPrependsEnvPrefixWhenMissing() {
+        // User types "MVN_PASSWORD" but template is "env:$VARIABLE_NAME"
+        assertEquals("env:MVN_PASSWORD", Init.applyTemplatePrefix("env:$VARIABLE_NAME", "MVN_PASSWORD"));
+    }
+
+    @Test
+    void applyTemplatePrefixDoesNotDuplicateExistingPrefix() {
+        // User types "env:MVN_PASSWORD" and template is "env:$VARIABLE_NAME"
+        assertEquals("env:MVN_PASSWORD", Init.applyTemplatePrefix("env:$VARIABLE_NAME", "env:MVN_PASSWORD"));
+    }
+
+    @Test
+    void applyTemplatePrefixHandlesSysPropertyPrefix() {
+        // User types "MY_PROP" but template is "sys-property:$PROPERTY_NAME"
+        assertEquals("sys-property:MY_PROP", Init.applyTemplatePrefix("sys-property:$PROPERTY_NAME", "MY_PROP"));
+    }
+
+    @Test
+    void applyTemplatePrefixDoesNotDuplicateSysPropertyPrefix() {
+        assertEquals(
+                "sys-property:MY_PROP",
+                Init.applyTemplatePrefix("sys-property:$PROPERTY_NAME", "sys-property:MY_PROP"));
+    }
+
+    @Test
+    void applyTemplatePrefixReturnsInputUnchangedWhenNoPlaceholder() {
+        // Template without $ placeholder — no prefix to apply
+        assertEquals("someValue", Init.applyTemplatePrefix("fixedValue", "someValue"));
+    }
+
+    @Test
+    void applyTemplatePrefixReturnsInputUnchangedWhenPlaceholderAtStart() {
+        // Template like "$VARIABLE" — prefix is empty, so nothing to prepend
+        assertEquals("MVN_PASSWORD", Init.applyTemplatePrefix("$VARIABLE_NAME", "MVN_PASSWORD"));
+    }
+
+    @Test
+    void applyTemplatePrefixHandlesCustomPrefix() {
+        // Arbitrary prefix before $
+        assertEquals("file:/path", Init.applyTemplatePrefix("file:$PATH", "/path"));
+    }
+
+    @Test
+    void applyTemplatePrefixDoesNotDuplicateCustomPrefix() {
+        assertEquals("file:/path", Init.applyTemplatePrefix("file:$PATH", "file:/path"));
+    }
+
+    @Test
+    void applyTemplatePrefixHandlesEmptyUserInput() {
+        // Empty user input — prefix should still be prepended
+        assertEquals("env:", Init.applyTemplatePrefix("env:$VARIABLE_NAME", ""));
+    }
+
+    @Test
+    void applyTemplatePrefixHandlesPrefixOnlyInput() {
+        // User enters just the prefix itself
+        assertEquals("env:", Init.applyTemplatePrefix("env:$VARIABLE_NAME", "env:"));
+    }
+}