Code coverage for `bun test` (#3975)

* WIP code coverage initial commit

* almost works

* one approach

* Code Coverage

* Update WebKit

* it works but is not yet accurate

* skip double ascii check

* wrapper

* it works but i'm not sure what to do about blocks

* hide blocks for now

* Update ZigSourceProvider.cpp

* Create coverage.md

* Update nav.ts

---------

Co-authored-by: Jarred Sumner <709451+Jarred-Sumner@users.noreply.github.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/src/bun.js/bindings/CodeCoverage.cpp b/src/bun.js/bindings/CodeCoverage.cpp
new file mode 100644
index 000000000..1cb3b6ba2
--- /dev/null
+++ b/src/bun.js/bindings/CodeCoverage.cpp
@@ -0,0 +1,44 @@
+#include "root.h"
+#include "ZigSourceProvider.h"
+#include <JavaScriptCore/ControlFlowProfiler.h>
+
+using namespace JSC;
+
+extern "C" bool CodeCoverage__withBlocksAndFunctions(
+    JSC::VM* vmPtr,
+    JSC::SourceID sourceID,
+    void* ctx,
+    bool ignoreSourceMap,
+    void (*blockCallback)(void* ctx, JSC::BasicBlockRange* range, size_t len, size_t functionOffset, bool ignoreSourceMap))
+{
+
+    VM& vm = *vmPtr;
+
+    auto basicBlocks = vm.controlFlowProfiler()->getBasicBlocksForSourceIDWithoutFunctionRange(
+        sourceID, vm);
+
+    if (basicBlocks.isEmpty()) {
+        blockCallback(ctx, nullptr, 0, 0, ignoreSourceMap);
+        return true;
+    }
+
+    size_t functionStartOffset = basicBlocks.size();
+
+    const Vector<std::tuple<bool, unsigned, unsigned>>& functionRanges = vm.functionHasExecutedCache()->getFunctionRanges(sourceID);
+
+    basicBlocks.reserveCapacity(functionRanges.size() + basicBlocks.size());
+
+    for (const auto& functionRange : functionRanges) {
+        BasicBlockRange range;
+        range.m_hasExecuted = std::get<0>(functionRange);
+        range.m_startOffset = static_cast<int>(std::get<1>(functionRange));
+        range.m_endOffset = static_cast<int>(std::get<2>(functionRange));
+        range.m_executionCount = range.m_hasExecuted
+            ? 1
+            : 0; // This is a hack. We don't actually count this.
+        basicBlocks.append(range);
+    }
+
+    blockCallback(ctx, basicBlocks.data(), basicBlocks.size(), functionStartOffset, ignoreSourceMap);
+    return true;
+}