fix: preserve existing template when adding parameters

src/test/ConfigUpdate.test.ts

@@ -0,0 +1,159 @@
+import { describe, it, expect } from 'vitest';
+import { Config } from '../models/Config';
+import { Env } from '../models/Env';
+import { EnvParam } from '../models/EnvParam';
+
+describe('Config Template Update', () => {
+  it('should preserve existing template when adding new parameter', () => {
+    // Arrange: Create config with existing template
+    const config = new Config();
+    const existingTemplate = `{
+  "existingKey": "existingValue",
+  "anotherKey": 123
+}`;
+    config.setTemplate(existingTemplate);
+    
+    const env = new Env(0, 'DEFAULT', [
+      new EnvParam(1, 'host', 'localhost'),
+      new EnvParam(2, 'port', '8080')
+    ]);
+    config.setEnvs([env]);
+
+    // Act: Update template from env (simulating adding parameters)
+    config.updateTemplateFromEnv(env);
+
+    // Assert: Template should have both existing content and new placeholders
+    const templateContent = config.template.content;
+    const templateObj = JSON.parse(templateContent);
+    
+    expect(templateObj.existingKey).toBe('existingValue');
+    expect(templateObj.anotherKey).toBe(123);
+    expect(templateObj['!!! host']).toBe('@host@');
+    expect(templateObj['!!! port']).toBe('@port@');
+  });
+
+  it('should not duplicate placeholders that already exist', () => {
+    // Arrange: Create config with template that already has placeholder
+    const config = new Config();
+    const existingTemplate = `{
+  "host": "@host@",
+  "port": 8080
+}`;
+    config.setTemplate(existingTemplate);
+    
+    const env = new Env(0, 'DEFAULT', [
+      new EnvParam(1, 'host', 'localhost'), // Already in template
+      new EnvParam(2, 'port', '8080')       // Already in template
+    ]);
+    config.setEnvs([env]);
+
+    // Act: Update template
+    config.updateTemplateFromEnv(env);
+
+    // Assert: Should not add !!! entries for existing placeholders
+    const templateContent = config.template.content;
+    // Count occurrences of @host@
+    const hostCount = (templateContent.match(/@host@/g) || []).length;
+    expect(hostCount).toBe(1); // Only original, no duplicate
+    
+    // Should preserve original structure
+    expect(templateContent).toContain('"host": "@host@"');
+  });
+
+  it('should initialize empty template', () => {
+    // Arrange: Create config with empty template
+    const config = new Config();
+    config.setTemplate('');
+    
+    const env = new Env(0, 'DEFAULT', [
+      new EnvParam(1, 'host', 'localhost')
+    ]);
+    config.setEnvs([env]);
+
+    // Act: Update template
+    config.updateTemplateFromEnv(env);
+
+    // Assert: Should create template with placeholder
+    const templateContent = config.template.content;
+    const templateObj = JSON.parse(templateContent);
+    expect(templateObj['!!! host']).toBe('@host@');
+  });
+
+  it('should not modify invalid JSON template', () => {
+    // Arrange: Create config with invalid JSON template
+    const config = new Config();
+    const invalidTemplate = `{
+  "key": "value"  // missing comma
+  "another": "key"
+}`;
+    config.setTemplate(invalidTemplate);
+    const originalTemplate = config.template.content;
+    
+    const env = new Env(0, 'DEFAULT', [
+      new EnvParam(1, 'host', 'localhost')
+    ]);
+    config.setEnvs([env]);
+
+    // Act: Update template (should not modify invalid JSON)
+    config.updateTemplateFromEnv(env);
+
+    // Assert: Template should remain unchanged
+    expect(config.template.content).toBe(originalTemplate);
+  });
+
+  it('should add multiple new placeholders to existing template', () => {
+    // Arrange
+    const config = new Config();
+    const existingTemplate = `{
+  "name": "myapp"
+}`;
+    config.setTemplate(existingTemplate);
+    
+    const env = new Env(0, 'DEFAULT', [
+      new EnvParam(1, 'host', 'localhost'),
+      new EnvParam(2, 'port', '8080'),
+      new EnvParam(3, 'user', 'admin')
+    ]);
+    config.setEnvs([env]);
+
+    // Act
+    config.updateTemplateFromEnv(env);
+
+    // Assert
+    const templateObj = JSON.parse(config.template.content);
+    expect(templateObj.name).toBe('myapp');
+    expect(templateObj['!!! host']).toBe('@host@');
+    expect(templateObj['!!! port']).toBe('@port@');
+    expect(templateObj['!!! user']).toBe('@user@');
+  });
+
+  it('should only add placeholders for params not in template', () => {
+    // Arrange: Template has @host@ but not @port@
+    const config = new Config();
+    config.setTemplate(`{
+  "host": "@host@",
+  "name": "test"
+}`);
+    
+    const env = new Env(0, 'DEFAULT', [
+      new EnvParam(1, 'host', 'localhost'), // In template
+      new EnvParam(2, 'port', '8080')       // Not in template
+    ]);
+    config.setEnvs([env]);
+
+    // Act
+    config.updateTemplateFromEnv(env);
+
+    // Assert
+    const templateContent = config.template.content;
+    const templateObj = JSON.parse(templateContent);
+    
+    // Should preserve original
+    expect(templateObj.host).toBe('@host@');
+    expect(templateObj.name).toBe('test');
+    
+    // Should add only missing
+    expect(templateObj['!!! port']).toBe('@port@');
+    expect(templateObj['!!! host']).toBeUndefined(); // Not added, already exists
+  });
+});