fix(cli): preserve comments in doc tests (#26828)

This commit makes comments in code snippets in JSDoc or markdown
preserved when they are executed as tests. In particular, this is needed
to get TypeScript special comments such as `@ts-ignore` or
`@ts-expect-error` to work correctly.

Fixes #26728

6 files changed, 45 insertions, 0 deletions

diff --git a/tests/specs/test/doc_ts_expect_error/__test__.jsonc b/tests/specs/test/doc_ts_expect_error/__test__.jsonc
new file mode 100644
index 000000000..ba64887a3
--- /dev/null
+++ b/tests/specs/test/doc_ts_expect_error/__test__.jsonc
@@ -0,0 +1,5 @@
+{
+  "args": "test --doc mod.ts",
+  "exitCode": 0,
+  "output": "mod.out"
+}
diff --git a/tests/specs/test/doc_ts_expect_error/mod.out b/tests/specs/test/doc_ts_expect_error/mod.out
new file mode 100644
index 000000000..d464d13d7
--- /dev/null
+++ b/tests/specs/test/doc_ts_expect_error/mod.out
@@ -0,0 +1,8 @@
+Check [WILDCARD]/mod.ts
+Check [WILDCARD]/mod.ts$2-10.ts
+running 0 tests from ./mod.ts
+running 1 test from ./mod.ts$2-10.ts
+[WILDCARD]/mod.ts$2-10.ts ... ok ([WILDCARD]ms)
+
+ok | 1 passed | 0 failed ([WILDCARD]ms)
+
diff --git a/tests/specs/test/doc_ts_expect_error/mod.ts b/tests/specs/test/doc_ts_expect_error/mod.ts
new file mode 100644
index 000000000..eeace602a
--- /dev/null
+++ b/tests/specs/test/doc_ts_expect_error/mod.ts
@@ -0,0 +1,13 @@
+/**
+ * ```ts
+ * import { add } from "./mod.ts";
+ *
+ * add(1, 2);
+ *
+ * // @ts-expect-error: can only add numbers
+ * add('1', '2');
+ * ```
+ */
+export function add(first: number, second: number) {
+  return first + second;
+}
diff --git a/tests/specs/test/markdown_ts_expect_error/__test__.jsonc b/tests/specs/test/markdown_ts_expect_error/__test__.jsonc
new file mode 100644
index 000000000..ad73f6df6
--- /dev/null
+++ b/tests/specs/test/markdown_ts_expect_error/__test__.jsonc
@@ -0,0 +1,5 @@
+{
+  "args": "test --doc main.md",
+  "exitCode": 0,
+  "output": "main.out"
+}
diff --git a/tests/specs/test/markdown_ts_expect_error/main.md b/tests/specs/test/markdown_ts_expect_error/main.md
new file mode 100644
index 000000000..9be70e919
--- /dev/null
+++ b/tests/specs/test/markdown_ts_expect_error/main.md
@@ -0,0 +1,8 @@
+# Documentation
+
+This test case checks if `@ts-expect-error` comment works as expected.
+
+```ts
+// @ts-expect-error
+const a: string = 42;
+```
diff --git a/tests/specs/test/markdown_ts_expect_error/main.out b/tests/specs/test/markdown_ts_expect_error/main.out
new file mode 100644
index 000000000..65990cd3f
--- /dev/null
+++ b/tests/specs/test/markdown_ts_expect_error/main.out
@@ -0,0 +1,6 @@
+Check [WILDCARD]/main.md$5-9.ts
+running 1 test from ./main.md$5-9.ts
+[WILDCARD]/main.md$5-9.ts ... ok ([WILDCARD]ms)
+
+ok | 1 passed | 0 failed ([WILDCARD]ms)
+