tests: Add tests for `settings.json` parsing

src/node/utils/Settings.js

@@ -825,5 +825,9 @@ exports.reloadSettings = () => {
   console.log(`Random string used for versioning assets: ${exports.randomVersionString}`);
 };
 
+exports.exportedForTestingOnly = {
+  parseSettings,
+};
+
 // initially load settings
 exports.reloadSettings();

src/tests/backend/specs/settings.js

@@ -0,0 +1,61 @@
+'use strict';
+
+const assert = require('assert').strict;
+const {parseSettings} = require('../../../node/utils/Settings').exportedForTestingOnly;
+const path = require('path');
+const process = require('process');
+
+describe(__filename, function () {
+  describe('parseSettings', function () {
+    let settings;
+    const envVarSubstTestCases = [
+      {name: 'true', val: 'true', var: 'SET_VAR_TRUE', want: true},
+      {name: 'false', val: 'false', var: 'SET_VAR_FALSE', want: false},
+      {name: 'null', val: 'null', var: 'SET_VAR_NULL', want: null},
+      {name: 'undefined', val: 'undefined', var: 'SET_VAR_UNDEFINED', want: undefined},
+      {name: 'number', val: '123', var: 'SET_VAR_NUMBER', want: 123},
+      {name: 'string', val: 'foo', var: 'SET_VAR_STRING', want: 'foo'},
+      {name: 'empty string', val: '', var: 'SET_VAR_EMPTY_STRING', want: ''},
+    ];
+
+    before(async function () {
+      for (const tc of envVarSubstTestCases) process.env[tc.var] = tc.val;
+      delete process.env.UNSET_VAR;
+      settings = parseSettings(path.join(__dirname, 'settings.json'), true);
+      assert(settings != null);
+    });
+
+    describe('environment variable substitution', function () {
+      describe('set', function () {
+        for (const tc of envVarSubstTestCases) {
+          it(tc.name, async function () {
+            const obj = settings['environment variable substitution'].set;
+            if (tc.name === 'undefined') {
+              assert(!(tc.name in obj));
+            } else {
+              assert.equal(obj[tc.name], tc.want);
+            }
+          });
+        }
+      });
+
+      describe('unset', function () {
+        it('no default', async function () {
+          const obj = settings['environment variable substitution'].unset;
+          assert.equal(obj['no default'], null);
+        });
+
+        for (const tc of envVarSubstTestCases) {
+          it(tc.name, async function () {
+            const obj = settings['environment variable substitution'].unset;
+            if (tc.name === 'undefined') {
+              assert(!(tc.name in obj));
+            } else {
+              assert.equal(obj[tc.name], tc.want);
+            }
+          });
+        }
+      });
+    });
+  });
+});

src/tests/backend/specs/settings.json

@@ -0,0 +1,39 @@
+// line comment
+/*
+ * block comment
+ */
+{
+  "trailing commas": {
+    "lists": {
+      "multiple lines": [
+        "",
+      ]
+    },
+    "objects": {
+      "multiple lines": {
+        "key": "",
+      }
+    }
+  },
+  "environment variable substitution": {
+    "set": {
+      "true": "${SET_VAR_TRUE}",
+      "false": "${SET_VAR_FALSE}",
+      "null": "${SET_VAR_NULL}",
+      "undefined": "${SET_VAR_UNDEFINED}",
+      "number": "${SET_VAR_NUMBER}",
+      "string": "${SET_VAR_STRING}",
+      "empty string": "${SET_VAR_EMPTY_STRING}"
+    },
+    "unset": {
+      "no default": "${UNSET_VAR}",
+      "true": "${UNSET_VAR:true}",
+      "false": "${UNSET_VAR:false}",
+      "null": "${UNSET_VAR:null}",
+      "undefined": "${UNSET_VAR:undefined}",
+      "number": "${UNSET_VAR:123}",
+      "string": "${UNSET_VAR:foo}",
+      "empty string": "${UNSET_VAR:}"
+    }
+  }
+}