Keep the colleague's microbu-esp32c5 tree in this repository

obu-firmware builds against vanetza-idf from microbu-esp32c5/external, but
that tree was gitignored, so a clone of this repository could not build the
firmware it ships. It is now committed here as ordinary files in its own
folder, microbu-esp32c5/: the colleague's commit cf4b99f plus the V2X2MAP
bridge's signature verification (--trust) used on the bench. Nothing is
fetched from or pushed to the colleague's repository; this repository and
its remotes carry everything. The folder's own .gitignore keeps build output,
downloaded components and private key material out, as it did there; the
committed file set is identical to that repository's tracked files.

The ESP32-C5 is still flashed from obu-firmware/, which only takes
vanetza-idf from microbu-esp32c5/, so the two stay separate folders.
FLASHING.md says how to take a newer version of the colleague's tree (copy
it over the folder, rebuild, test, commit).

microbu-esp32c5/external/vanetza-idf/vanetza/net/tests/osi_layer.cpp

@@ -0,0 +1,102 @@
+#include <gtest/gtest.h>
+#include <vanetza/net/osi_layer.hpp>
+
+using namespace vanetza;
+
+TEST(OsiLayer, ordering) {
+    EXPECT_LT(OsiLayer::Physical, OsiLayer::Link);
+    EXPECT_LT(OsiLayer::Link, OsiLayer::Network);
+    EXPECT_LT(OsiLayer::Network, OsiLayer::Transport);
+    EXPECT_LT(OsiLayer::Transport, OsiLayer::Session);
+    EXPECT_LT(OsiLayer::Session, OsiLayer::Presentation);
+    EXPECT_LT(OsiLayer::Presentation, OsiLayer::Application);
+
+    EXPECT_EQ(min_osi_layer(), OsiLayer::Physical);
+    EXPECT_EQ(max_osi_layer(), OsiLayer::Application);
+}
+
+TEST(OsiLayer, comparison) {
+    EXPECT_LT(OsiLayer::Physical, OsiLayer::Link);
+    EXPECT_GT(OsiLayer::Link, OsiLayer::Physical);
+    EXPECT_EQ(OsiLayer::Physical, OsiLayer::Physical);
+    EXPECT_NE(OsiLayer::Physical, OsiLayer::Link);
+    EXPECT_LE(OsiLayer::Physical, OsiLayer::Physical);
+    EXPECT_GE(OsiLayer::Link, OsiLayer::Link);
+}
+
+TEST(OsiLayer, list) {
+    auto list = osi_layers;
+    ASSERT_EQ(list.size(), 7);
+
+    auto it = list.begin();
+    EXPECT_EQ(OsiLayer::Physical, *it++);
+    EXPECT_EQ(OsiLayer::Link, *it++);
+    EXPECT_EQ(OsiLayer::Network, *it++);
+    EXPECT_EQ(OsiLayer::Transport, *it++);
+    EXPECT_EQ(OsiLayer::Session, *it++);
+    EXPECT_EQ(OsiLayer::Presentation, *it++);
+    EXPECT_EQ(OsiLayer::Application, *it++);
+    EXPECT_EQ(list.end(), it);
+
+    auto prev = list.begin();
+    for (it = prev + 1; it != list.end(); prev = it, ++it) {
+        EXPECT_LT(*prev, *it);
+    }
+}
+
+TEST(OsiLayer, num) {
+    EXPECT_EQ(7, num_osi_layers(min_osi_layer(), max_osi_layer()));
+    EXPECT_EQ(1, num_osi_layers(OsiLayer::Link, OsiLayer::Link));
+    EXPECT_EQ(2, num_osi_layers(OsiLayer::Link, OsiLayer::Network));
+    EXPECT_EQ(0, num_osi_layers(OsiLayer::Network, OsiLayer::Link));
+}
+
+TEST(OsiLayer, distance) {
+    EXPECT_EQ(0, distance(OsiLayer::Session, OsiLayer::Session));
+    EXPECT_EQ(1, distance(OsiLayer::Network, OsiLayer::Transport));
+    EXPECT_EQ(-1, distance(OsiLayer::Transport, OsiLayer::Network));
+    EXPECT_EQ(num_osi_layers(min_osi_layer(), max_osi_layer()) - 1,
+        distance(min_osi_layer(), max_osi_layer()));
+}
+
+TEST(OsiLayer, compile_time_range) {
+    const auto r1_ref = osi_layers;
+    ASSERT_EQ(7, r1_ref.size());
+    auto r1 = osi_layer_range<min_osi_layer(), max_osi_layer()>();
+    EXPECT_EQ(r1_ref.size(), r1.size());
+    for (unsigned i = 0; i < r1.size(); ++i) {
+        EXPECT_EQ(r1_ref[i], r1[i]);
+    }
+
+    auto r2 = osi_layer_range<OsiLayer::Link, OsiLayer::Transport>();
+    ASSERT_EQ(3, r2.size());
+    EXPECT_EQ(OsiLayer::Link, r2[0]);
+    EXPECT_EQ(OsiLayer::Network, r2[1]);
+    EXPECT_EQ(OsiLayer::Transport, r2[2]);
+
+    auto r3 = osi_layer_range<OsiLayer::Application, OsiLayer::Application>();
+    EXPECT_EQ(1, r3.size());
+}
+
+TEST(OsiLayer, run_time_range) {
+    const auto r1_ref = osi_layers;
+    ASSERT_EQ(7, r1_ref.size());
+    auto r1 = osi_layer_range(min_osi_layer(), max_osi_layer());
+    EXPECT_EQ(r1_ref.size(), r1.size());
+    for (unsigned i = 0; i < r1.size(); ++i) {
+        EXPECT_EQ(r1_ref[i], r1[i]);
+    }
+
+    auto r2 = osi_layer_range(OsiLayer::Link, OsiLayer::Transport);
+    ASSERT_EQ(3, r2.size());
+    EXPECT_EQ(OsiLayer::Link, r2[0]);
+    EXPECT_EQ(OsiLayer::Network, r2[1]);
+    EXPECT_EQ(OsiLayer::Transport, r2[2]);
+
+    auto r3 = osi_layer_range(OsiLayer::Application, OsiLayer::Application);
+    ASSERT_EQ(1, r3.size());
+    EXPECT_EQ(OsiLayer::Application, r3[0]);
+
+    auto r4 = osi_layer_range(OsiLayer::Application, OsiLayer::Transport);
+    EXPECT_EQ(0, r4.size());
+}