Add Drawing and its test (#20)

* Move class `Drawing` from the main file and add tests

* Add Prettier and configs to enforce the code format being consistent with the existing one

* Remove redundant logic from Drawing class and simplify its tests

* Fix format issues

* Fix format issues

* Update test case and reformat files

Author: realtomkwok

.gitignore

@@ -1,3 +1,4 @@
 .terraform*
 *.tfstate*
-tfplan
+tfplan
+/.idea/

backend/.gitignore

@@ -27,7 +27,7 @@ lib-cov
 coverage
 *.lcov
 
-# nyc test coverage
+# nyc __test__ coverage
 .nyc_output
 
 # Grunt intermediate storage (https://gruntjs.com/creating-plugins#storing-task-files)

backend/.prettierignore

@@ -0,0 +1,3 @@
+dist
+build
+coverage

backend/.prettierrc

@@ -0,0 +1,6 @@
+{
+    "singleQuote": true,
+    "useTabs": false,
+    "tabWidth": 2,
+    "semi": false
+}

backend/jest.config.ts

@@ -0,0 +1,53 @@
+/**
+ * Check https://github.com/LivingLimes/draw-freely/pull/18#issuecomment-2731114582 for a brief explanation on the configurations set below
+ *
+ * For a detailed explanation regarding each configuration property, visit:
+ * https://jestjs.io/docs/configuration
+ */
+
+import type { Config } from 'jest';
+
+const config: Config = {
+  // Coverage
+  collectCoverage: true,
+  coverageDirectory: './__test__/coverage',
+  coveragePathIgnorePatterns: ['/node_modules/'],
+  coverageProvider: 'v8',
+  coverageReporters: ['json', 'text', 'lcov', 'clover', 'text-summary'],
+  // Jest will fail if there is less than 80% branch, line, and function coverage, or if there are more than 10 uncovered statements:
+  coverageThreshold: {
+    global: {
+      branches: 80,
+      functions: 80,
+      lines: 80,
+      statements: -10,
+    },
+  },
+
+  // Test Environment
+  testEnvironment: 'jest-environment-node',
+  testEnvironmentOptions: {},
+  testMatch: ['**/__tests__/**/*.[jt]s?(x)', '**/?(*.)+(spec|test).[tj]s?(x)'],
+  testPathIgnorePatterns: ['/node_modules/'],
+
+  // Miscellaneous
+  moduleFileExtensions: [
+    'ts',
+    'tsx',
+    'js',
+    'jsx',
+    'mjs',
+    'cjs',
+    'json',
+    'node',
+  ],
+  // The root directory that Jest should scan for tests and modules within
+  rootDir: 'src',
+  transform: {
+    '\\.[jt]sx?$': 'ts-jest',
+  },
+  verbose: true,
+  watchman: true,
+};
+
+export default config;