Simplify local testing inside Docker environment (#2777)

* Docs + changes to Dockerfile for running tests while avoiding rebuilding on every change.

* more notes

* lint

* typo

DEVELOPING.md

@@ -63,6 +63,19 @@ To run these tests, run [`./tests.sh`](./tests.sh). You can filter the tests to
 
 To invoke cross-architecture tests, use `./qemu-tests.sh`, and to run unit tests, use `./unit-tests.sh`
 
+To run the tests in the same environment as the testing CI/CD, you can use the following Docker command.
+
+```sh
+# General test suite
+docker compose run --rm --build ubuntu24.04-mount ./tests.sh
+# Cross-architecture tests
+docker compose run --rm --build ubuntu24.04-mount ./qemu-tests.sh
+```
+
+This comes in handy particularly for cross-architecture tests because the Docker environment has all the cross-compilers installed. The active `pwndbg` directory is mounted, preventing the need for a full rebuild whenever you update the codebase.
+
+Remove the `-mount` if you want the tests to run from a clean slate (no files are mounted, meaning all binaries are recompiled each time).
+
 ## Writing Tests
 
 Each test is a Python function that runs inside of an isolated GDB session. 

Dockerfile

@@ -9,7 +9,7 @@
 #
 
 ARG image=mcr.microsoft.com/devcontainers/base:jammy
-FROM $image
+FROM $image AS base
 
 WORKDIR /pwndbg
 
@@ -45,6 +45,8 @@ RUN ./setup-dev.sh
 # Cleanup dummy files
 RUN rm README.md && rm -rf pwndbg
 
+FROM base AS full
+
 ADD . /pwndbg/
 
 ARG LOW_PRIVILEGE_USER="vscode"

docker-compose.yml

@@ -1,4 +1,3 @@
-version: "3.8"
 services:
   base: &base-spec
     build: .
@@ -28,6 +27,16 @@ services:
       args:
         image: ubuntu:24.04
 
+  ubuntu24.04-mount:
+    <<: *base-spec
+    build:
+      context: .
+      target: base
+      dockerfile: Dockerfile
+      args:
+        image: ubuntu:24.04
+    volumes:
+      - .:/pwndbg
 
   debian12:
     <<: *base-spec