Document per-test-relay-selection feature in `docs/`

Small update to docs

1 files changed, 40 insertions, 10 deletions

diff --git a/test/test-manager/docs/config.md b/test/test-manager/docs/config.md
index 8c4db7fce4..09d4f110ce 100644
--- a/test/test-manager/docs/config.md
+++ b/test/test-manager/docs/config.md
@@ -2,39 +2,68 @@
 
 This document outlines the format of the configuration used by `test-manager` to perform end-to-end tests in virtualized environments.
 
-# Format
+## Format
+
+The configuration is a JSON document with three values:
 
-The configuration is a JSON document with two values:
 ```json
 {
     "mullvad_host": <optional string>,
-    "vms": <document>
+    "vms": <document>,
+    "test_locations": [ {"test_name": ["relay"] }, .. ],
 }
 ```
 
 The configurable values are prone to change, and for the time being it is probably a good idea to get acquainted with the [Rust struct called "Config"](../src/config.rs) from which the configuration is serialized.
-To get started, `test-manager` provides the `test-manager set` command to add and edit VM configurations.
+To get started, `test-manager` provides the `test-manager config vm set` command to add and edit VM configurations.
 It is also recommended to view the [example section](#Examples) further down this document.
 
-# Location
+## Location
 
 The configuration is assumed to exist in `$XDG_CONFIG_HOME/mullvad-test/config.json` (most likely `$HOME/.config/mullvad-test/config.json`) on Linux and `$HOME/Library/Application Support/mullvad-test/config.json` on macOS.
 
-# Examples
+## Per-test relay selection
+
+It is possible to configure which relay(s) should be selected on a test-per-test basis by providing the `test_locations`
+configuration option. If no explicit configuration is given, no assumption will be made from within the tests themselves.
+
+The format is a list of maps with a single key-value pair, where the key is a [glob pattern](<https://en.wikipedia.org/wiki/Glob_(programming)>)
+that will be matched against the test name, and the value is a list of locations to use for the matching tests.
+The name of the locations are the same as for the `mullvad relay set location` CLI-command.
+
+### Example
+
+```json
+{
+  // other fields
+  "test_locations": [
+    { "*daita*": ["se-got-wg-001", "se-got-wg-002"] },
+    { "*": ["se"] }
+  ]
+}
+```
+
+The above example will set the locations for the test `test_daita` to a custom list
+containing `se-got-wg-001` and `se-got-wg-002`. The `*` is a wildcard that will match
+any test name. The configuration is read from top-to-bottom, and the first match will be used.
+
+## Example configurations
 
-## Minimal
+### Minimal
 
 The minimal valid configuration does not contain any virtual machines
+
 ```json
 {
-    "mullvad_host": "stagemole.eu",
-    "vms": { }
+  "mullvad_host": "stagemole.eu",
+  "vms": {}
 }
 ```
 
-## Complete
+### Complete
 
 A configuration containing one Debian 12 VM and one Windows 11 VM
+
 ```json
 {
     "mullvad_host": "stagemole.eu",
@@ -68,5 +97,6 @@ A configuration containing one Debian 12 VM and one Windows 11 VM
             "tpm": false
         }
     }
+  }
 }
 ```