Start testing AppSettings

test/server/lib/AppSettings.ts

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+import { AppSettings } from 'app/server/lib/AppSettings';
+import { EnvironmentSnapshot } from '../testUtils';
+
+import { assert } from 'chai';
+
+describe('AppSettings', () => {
+  let appSettings: AppSettings;
+  let env: EnvironmentSnapshot;
+  beforeEach(() => {
+    appSettings = new AppSettings('test');
+    env = new EnvironmentSnapshot();
+  });
+
+  afterEach(() => {
+    env.restore();
+  });
+
+  describe('for integers', () => {
+    function testIntMethod(method: 'readInt' | 'requireInt') {
+      it('should throw an error if the value is less than the minimum', () => {
+        process.env.TEST = '4';
+        assert.throws(() => {
+          appSettings[method]({ envVar: 'TEST', minValue: 5 });
+        }, 'value 4 is less than minimum 5');
+      });
+
+      it('should throw an error if the value is greater than the maximum', () => {
+        process.env.TEST = '6';
+        assert.throws(() => {
+          appSettings[method]({ envVar: 'TEST', maxValue: 5 });
+        }, 'value 6 is greater than maximum 5');
+      });
+
+      it('should throw if the value is NaN', () => {
+        process.env.TEST = 'not a number';
+        assert.throws(() => appSettings[method]({ envVar: 'TEST' }), 'not a number does not look like a number');
+      });
+
+      it('should throw if the default value is not finite', () => {
+        assert.throws(
+          () => appSettings[method]({ envVar: 'TEST', defaultValue: Infinity }),
+          'Infinity does not look like a number'
+        );
+      });
+
+      it('should throw if the default value is not within the range', () => {
+        assert.throws(
+          () => appSettings[method]({
+            envVar: 'TEST',
+            defaultValue: 6,
+            minValue: 7,
+            maxValue: 9,
+          }),
+          'value 6 is less than minimum 7'
+        );
+      });
+
+      it('should return the default value if it is within the range', () => {
+        const result = appSettings[method]({
+          envVar: 'TEST',
+          defaultValue: 5,
+          minValue: 5,
+          maxValue: 12
+        });
+        assert.strictEqual(result, 5);
+      });
+
+      it('should return the value if it is within the range', () => {
+        process.env.TEST = '5';
+        assert.strictEqual(appSettings[method]({ envVar: 'TEST', minValue: 5 }), 5);
+      });
+
+      it('should return the integer value of a float', () => {
+        process.env.TEST = '5.9';
+        assert.strictEqual(appSettings[method]({ envVar: 'TEST' }), 5);
+      });
+    }
+
+    describe('readInt()', () => {
+      testIntMethod('readInt');
+
+      it('should return undefined when no value nor default value is passed', () => {
+        const result = appSettings.readInt({ envVar: 'TEST', maxValue: 5 });
+        assert.isUndefined(result);
+      });
+    });
+
+    describe('requireInt()', () => {
+      testIntMethod('requireInt');
+
+      it('should throw if env variable is not set and no default value is passed', () => {
+        assert.throws(() => appSettings.requireInt({ envVar: 'TEST' }), 'missing environment variable: TEST');
+      });
+    });
+  });
+});