tcp: add netsim test.

This test simulates a network with a given latency and packet loss, and measures the
throughput between two virtual smoltcp instances.

.github/workflows/test.yml

@@ -7,7 +7,7 @@ name: Test
 jobs:
   tests:
     runs-on: ubuntu-22.04
-    needs: [check-msrv, test-msrv, test-stable, clippy]
+    needs: [check-msrv, test-msrv, test-stable, clippy, test-netsim]
     steps:
       - name: Done
         run: exit 0
@@ -48,6 +48,14 @@ jobs:
       - name: Run Tests nightly
         run: ./ci.sh test nightly
 
+  test-netsim:
+    runs-on: ubuntu-22.04
+    continue-on-error: true
+    steps:
+      - uses: actions/checkout@v4
+      - name: Run network-simulation tests
+        run: ./ci.sh netsim
+
   test-build-16bit:
     runs-on: ubuntu-22.04
     continue-on-error: true

Cargo.toml

@@ -35,6 +35,8 @@ getopts = "0.2"
 rand = "0.8"
 url = "2.0"
 rstest = "0.17"
+insta = "1.41.1"
+rand_chacha = "0.3.1"
 
 [features]
 std = ["managed/std", "alloc"]

ci.sh

@@ -49,16 +49,20 @@ test() {
     rustup toolchain install $version
 
     for features in ${FEATURES_TEST[@]}; do
-        cargo +$version test --no-default-features --features "$features"
+        cargo +$version test --no-default-features --features "$features" -- --skip netsim
     done
 
     if [[ $version == "nightly" ]]; then
         for features in ${FEATURES_TEST_NIGHTLY[@]}; do
-            cargo +$version test --no-default-features --features "$features"
+            cargo +$version test --no-default-features --features "$features" -- --skip netsim
         done
     fi
 }
 
+netsim() {
+    cargo test --release netsim
+}
+
 check() {
     local version=$1
     rustup toolchain install $version
@@ -138,3 +142,7 @@ fi
 if [[ $1 == "coverage" || $1 == "all" ]]; then
     coverage
 fi
+
+if [[ $1 == "netsim" || $1 == "all" ]]; then
+    netsim
+fi