feat: add exit sanitizer to Deno.test (#9529)

This adds an exit sanitizer to ensure that code being tested or 
dependencies of that code can't accidentally call "Deno.exit"
leading to partial test runs and false results.

2 files changed, 41 insertions, 1 deletions

diff --git a/runtime/js/30_os.js b/runtime/js/30_os.js
index 236131432..23c3d8de6 100644
--- a/runtime/js/30_os.js
+++ b/runtime/js/30_os.js
@@ -24,6 +24,13 @@
     return core.jsonOpSync("op_system_cpu_info");
   }
 
+  // This is an internal only method used by the test harness to override the
+  // behavior of exit when the exit sanitizer is enabled.
+  let exitHandler = null;
+  function setExitHandler(fn) {
+    exitHandler = fn;
+  }
+
   function exit(code = 0) {
     // Dispatches `unload` only when it's not dispatched yet.
     if (!window[Symbol.for("isUnloadDispatched")]) {
@@ -31,6 +38,12 @@
       // ref: https://github.com/denoland/deno/issues/3603
       window.dispatchEvent(new Event("unload"));
     }
+
+    if (exitHandler) {
+      exitHandler(code);
+      return;
+    }
+
     core.jsonOpSync("op_exit", { code });
     throw new Error("Code not reachable");
   }
@@ -63,6 +76,7 @@
   window.__bootstrap.os = {
     env,
     execPath,
+    setExitHandler,
     exit,
     osRelease,
     systemMemoryInfo,
diff --git a/runtime/js/40_testing.js b/runtime/js/40_testing.js
index 2258dc7b6..eec75f133 100644
--- a/runtime/js/40_testing.js
+++ b/runtime/js/40_testing.js
@@ -4,7 +4,7 @@
 ((window) => {
   const core = window.Deno.core;
   const colors = window.__bootstrap.colors;
-  const { exit } = window.__bootstrap.os;
+  const { setExitHandler, exit } = window.__bootstrap.os;
   const { Console, inspectArgs } = window.__bootstrap.console;
   const { stdout } = window.__bootstrap.files;
   const { exposeForTest } = window.__bootstrap.internals;
@@ -86,6 +86,27 @@ finishing test case.`;
     };
   }
 
+  // Wrap test function in additional assertion that makes sure
+  // that the test case does not accidentally exit prematurely.
+  function assertExit(fn) {
+    return async function exitSanitizer() {
+      setExitHandler((exitCode) => {
+        assert(
+          false,
+          `Test case attempted to exit with exit code: ${exitCode}`,
+        );
+      });
+
+      try {
+        await fn();
+      } catch (err) {
+        throw err;
+      } finally {
+        setExitHandler(null);
+      }
+    };
+  }
+
   const TEST_REGISTRY = [];
 
   // Main test function provided by Deno, as you can see it merely
@@ -100,6 +121,7 @@ finishing test case.`;
       only: false,
       sanitizeOps: true,
       sanitizeResources: true,
+      sanitizeExit: true,
     };
 
     if (typeof t === "string") {
@@ -128,6 +150,10 @@ finishing test case.`;
       testDef.fn = assertResources(testDef.fn);
     }
 
+    if (testDef.sanitizeExit) {
+      testDef.fn = assertExit(testDef.fn);
+    }
+
     TEST_REGISTRY.push(testDef);
   }