From a86db5d0d15f736ec25229ddde62859ea15f306e Mon Sep 17 00:00:00 2001
From: Andrei Listochkin <andrei.listochkin@ferrous-systems.com>
Date: Wed, 11 May 2022 13:22:58 +0100
Subject: iterative dependency solver

First, we go through every environment variable key and record all cases
where there are reference to other variables / dependencies.

We track two sets of variables - resolved and yet-to-be-resolved.
We pass over a list of variables over and over again and when all
variable's dependencies were resolved during previous passes we perform
a replacement for that variable, too.

Over time the size of `toResolve` set should go down to zero, however
circular dependencies may prevent that. We track the size of `toResolve`
between iterations to avoid infinite looping.

At the end we produce an object of the same size and shape as
the original, but with the values replace with resolved versions.
---
 editors/code/tests/unit/settings.test.ts | 41 ++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 editors/code/tests/unit/settings.test.ts

(limited to 'editors/code/tests')

diff --git a/editors/code/tests/unit/settings.test.ts b/editors/code/tests/unit/settings.test.ts
new file mode 100644
index 00000000000..12734d15667
--- /dev/null
+++ b/editors/code/tests/unit/settings.test.ts
@@ -0,0 +1,41 @@
+import * as assert from 'assert';
+import { Context } from '.';
+import { substituteVariablesInEnv } from '../../src/config';
+
+export async function getTests(ctx: Context) {
+    await ctx.suite('Server Env Settings', suite => {
+        suite.addTest('Replacing Env Variables', async () => {
+            const envJson = {
+                USING_MY_VAR: "${env:MY_VAR} test ${env:MY_VAR}",
+                MY_VAR: "test"
+            };
+            const expectedEnv = {
+                USING_MY_VAR: "test test test",
+                MY_VAR: "test"
+            };
+            const actualEnv = await substituteVariablesInEnv(envJson);
+            assert.deepStrictEqual(actualEnv, expectedEnv);
+        });
+
+        suite.addTest('Circular dependencies remain as is', async () => {
+            const envJson = {
+                A_USES_B: "${env:B_USES_A}",
+                B_USES_A: "${env:A_USES_B}",
+                C_USES_ITSELF: "${env:C_USES_ITSELF}",
+                D_USES_C: "${env:C_USES_ITSELF}",
+                E_IS_ISOLATED: "test",
+                F_USES_E: "${env:E_IS_ISOLATED}"
+            };
+            const expectedEnv = {
+                A_USES_B: "${env:B_USES_A}",
+                B_USES_A: "${env:A_USES_B}",
+                C_USES_ITSELF: "${env:C_USES_ITSELF}",
+                D_USES_C: "${env:C_USES_ITSELF}",
+                E_IS_ISOLATED: "test",
+                F_USES_E: "test"
+            };
+            const actualEnv = await substituteVariablesInEnv(envJson);
+            assert.deepStrictEqual(actualEnv, expectedEnv);
+        });
+    });
+}
-- 
cgit 1.4.1-3-g733a5