diff --git a/tests/testBehavior.cpp b/tests/testBehavior.cpp
new file mode 100644
index 0000000..4b51140
--- /dev/null
+++ b/tests/testBehavior.cpp
@@ -0,0 +1,158 @@
+#include "testHarness.h"
+#include "vf/Behavior.h"
+
+#include <memory>
+#include <string>
+#include <vector>
+
+using namespace vf;
+
+namespace {
+
+World flatWorld(int halfSpan = 24) {
+    World world;
+    for (int x = -halfSpan; x <= halfSpan; ++x) {
+        for (int z = -halfSpan; z <= halfSpan; ++z) world.setBlock(x, 0, z, Block::Stone);
+    }
+    return world;
+}
+
+World grassWorld(int halfSpan = 12) {
+    World world;
+    for (int x = -halfSpan; x <= halfSpan; ++x) {
+        for (int z = -halfSpan; z <= halfSpan; ++z) world.setBlock(x, 0, z, Block::Grass);
+    }
+    return world;
+}
+
+std::unique_ptr<BehaviorNode> constantAction(const char* name, BehaviorStatus status, int* counter) {
+    return std::unique_ptr<BehaviorNode>(new ActionNode(name, [status, counter](BehaviorContext&) {
+        if (counter != nullptr) ++(*counter);
+        return status;
+    }));
+}
+
+std::unique_ptr<BehaviorNode> flagCondition(const char* name, const bool* source) {
+    return std::unique_ptr<BehaviorNode>(
+        new ConditionNode(name, [source](BehaviorContext&) { return *source; }));
+}
+
+// Reports Running for `runningTicks` calls, then Success once, then restarts.
+std::unique_ptr<BehaviorNode> slowAction(const char* name, int runningTicks, int* counter,
+                                         int* progress) {
+    return std::unique_ptr<BehaviorNode>(
+        new ActionNode(name, [runningTicks, counter, progress](BehaviorContext&) {
+            ++(*counter);
+            ++(*progress);
+            if (*progress <= runningTicks) return BehaviorStatus::Running;
+            *progress = 0;
+            return BehaviorStatus::Success;
+        }));
+}
+
+BehaviorContext freshContext(const World* world) {
+    BehaviorContext ctx;
+    ctx.world = world;
+    return ctx;
+}
+
+BehaviorAgent makeAgent(Species species, const Vec3& position) {
+    BehaviorAgent agent;
+    agent.species = species;
+    agent.position = position;
+    agent.homePosition = position;
+    const SpeciesStats& stats = speciesStats(species);
+    agent.health = stats.maxHealth;
+    agent.maxHealth = stats.maxHealth;
+    agent.moveStep = 0.25f;
+    return agent;
+}
+
+} // namespace
+
+VF_TEST(blackboardKeepsEachValueTypeInItsOwnDrawer) {
+    Blackboard board;
+    board.setNumber("threat", 4.5f);
+    board.setCount("meals", 3);
+    board.setFlag("engaged", true);
+    board.setPoint("lastSeen", Vec3{1.0f, 2.0f, 3.0f});
+    board.setCell("target", Vec3i{4, 5, 6});
+    board.setRoute("path", {Vec3i{0, 1, 0}, Vec3i{1, 1, 0}});
+
+    CHECK_NEAR(board.number("threat"), 4.5f, 1e-6f);
+    CHECK_EQ(board.count("meals"), 3);
+    CHECK(board.flag("engaged"));
+    CHECK_NEAR(board.point("lastSeen").y, 2.0f, 1e-6f);
+    CHECK(board.cell("target") == Vec3i(4, 5, 6));
+    CHECK(board.route("path") != nullptr);
+    CHECK_EQ(board.route("path")->size(), 2u);
+    CHECK_EQ(board.entryCount(), 6u);
+
+    // A key written as one type is invisible to every other type.
+    CHECK(!board.hasCount("threat"));
+    CHECK(!board.hasNumber("meals"));
+    CHECK(board.route("threat") == nullptr);
+    CHECK_NEAR(board.number("missing", -1.0f), -1.0f, 1e-6f);
+
+    board.eraseNumber("threat");
+    CHECK(!board.hasNumber("threat"));
+    CHECK_EQ(board.entryCount(), 5u);
+    board.eraseRoute("path");
+    CHECK(!board.hasRoute("path"));
+
+    board.clear();
+    CHECK_EQ(board.entryCount(), 0u);
+}
+
+VF_TEST(sequenceStopsAtTheChildThatFailsAndSkipsTheRest) {
+    int firstRuns = 0;
+    int lastRuns = 0;
+    bool gateOpen = false;
+
+    auto root = std::unique_ptr<SequenceNode>(new SequenceNode("sequence"));
+    root->add(constantAction("first", BehaviorStatus::Success, &firstRuns));
+    root->add(flagCondition("gate", &gateOpen));
+    root->add(constantAction("last", BehaviorStatus::Success, &lastRuns));
+
+    BehaviorTree tree(std::move(root));
+    BehaviorContext ctx;
+
+    CHECK(tree.tick(ctx) == BehaviorStatus::Failure);
+    CHECK_EQ(firstRuns, 1);
+    CHECK_EQ(lastRuns, 0);
+
+    gateOpen = true;
+    CHECK(tree.tick(ctx) == BehaviorStatus::Success);
+    CHECK_EQ(firstRuns, 2);
+    CHECK_EQ(lastRuns, 1);
+}
+
+VF_TEST(selectorTakesTheFirstBranchThatSucceedsAndFailsWhenNoneDo) {
+    int firstRuns = 0;
+    int secondRuns = 0;
+    int thirdRuns = 0;
+
+    auto root = std::unique_ptr<SelectorNode>(new SelectorNode("selector"));
+    root->add(constantAction("first", BehaviorStatus::Failure, &firstRuns));
+    root->add(constantAction("second", BehaviorStatus::Success, &secondRuns));
+    root->add(constantAction("third", BehaviorStatus::Success, &thirdRuns));
+
+    BehaviorTree tree(std::move(root));
+    BehaviorContext ctx;
+    CHECK(tree.tick(ctx) == BehaviorStatus::Success);
+    CHECK_EQ(firstRuns, 1);
+    CHECK_EQ(secondRuns, 1);
+    CHECK_EQ(thirdRuns, 0);
+
+    auto allFail = std::unique_ptr<SelectorNode>(new SelectorNode("selector"));
+    allFail->add(constantAction("a", BehaviorStatus::Failure, nullptr));
+    allFail->add(constantAction("b", BehaviorStatus::Failure, nullptr));
+    BehaviorTree hopeless(std::move(allFail));
+    CHECK(hopeless.tick(ctx) == BehaviorStatus::Failure);
+}
+
+VF_TEST(aRunningNodeResumesNextTickInsteadOfRestartingTheSequence) {
+    int firstRuns = 0;
+    int slowRuns = 0;
+    int slowProgress = 0;
+