From ab67b4c645dc34619e09c2f9f36c18122b11a307 Mon Sep 17 00:00:00 2001
From: Nathan Whitaker <17734409+nathanwhit@users.noreply.github.com>
Date: Fri, 15 Mar 2024 20:58:57 -0700
Subject: [PATCH] fix(coverage): Error if no files are included in the report
 (#22952)

Fixes #22941.

In that case, the only file with coverage was the `test.ts` file. The
coverage reporter filters out test files before compiling its report, so
after filtering we were left with an empty set of files. Later on it's
assumed that there is at least 1 file to be reported on, and we panic.
Instead of panicking, just issue an error after filtering.
---
 cli/tools/coverage/mod.rs                         |  3 +++
 .../coverage/no_files_after_filter/__test__.jsonc | 15 +++++++++++++++
 .../no_files_after_filter/no_files_in_report.out  |  1 +
 .../specs/coverage/no_files_after_filter/test.ts  |  1 +
 .../no_files_after_filter/test_coverage.out       |  6 ++++++
 5 files changed, 26 insertions(+)
 create mode 100644 tests/specs/coverage/no_files_after_filter/__test__.jsonc
 create mode 100644 tests/specs/coverage/no_files_after_filter/no_files_in_report.out
 create mode 100644 tests/specs/coverage/no_files_after_filter/test.ts
 create mode 100644 tests/specs/coverage/no_files_after_filter/test_coverage.out

diff --git a/cli/tools/coverage/mod.rs b/cli/tools/coverage/mod.rs
index e5bd3ae2e2..b076895700 100644
--- a/cli/tools/coverage/mod.rs
+++ b/cli/tools/coverage/mod.rs
@@ -485,6 +485,9 @@ pub async fn cover_files(
     coverage_flags.exclude,
     npm_resolver.as_ref(),
   );
+  if script_coverages.is_empty() {
+    return Err(generic_error("No covered files included in the report"));
+  }
 
   let proc_coverages: Vec<_> = script_coverages
     .into_iter()
diff --git a/tests/specs/coverage/no_files_after_filter/__test__.jsonc b/tests/specs/coverage/no_files_after_filter/__test__.jsonc
new file mode 100644
index 0000000000..e8aa477a89
--- /dev/null
+++ b/tests/specs/coverage/no_files_after_filter/__test__.jsonc
@@ -0,0 +1,15 @@
+{
+  "tempDir": true,
+  "steps": [
+    {
+      "args": "test --coverage test.ts",
+      "output": "test_coverage.out",
+      "exitCode": 0
+    },
+    {
+      "args": "coverage ./coverage",
+      "output": "no_files_in_report.out",
+      "exitCode": 1
+    }
+  ]
+}
diff --git a/tests/specs/coverage/no_files_after_filter/no_files_in_report.out b/tests/specs/coverage/no_files_after_filter/no_files_in_report.out
new file mode 100644
index 0000000000..c9ba7af951
--- /dev/null
+++ b/tests/specs/coverage/no_files_after_filter/no_files_in_report.out
@@ -0,0 +1 @@
+error: No covered files included in the report
diff --git a/tests/specs/coverage/no_files_after_filter/test.ts b/tests/specs/coverage/no_files_after_filter/test.ts
new file mode 100644
index 0000000000..03818ae8d4
--- /dev/null
+++ b/tests/specs/coverage/no_files_after_filter/test.ts
@@ -0,0 +1 @@
+Deno.test("test", () => {});
diff --git a/tests/specs/coverage/no_files_after_filter/test_coverage.out b/tests/specs/coverage/no_files_after_filter/test_coverage.out
new file mode 100644
index 0000000000..3c598f62e1
--- /dev/null
+++ b/tests/specs/coverage/no_files_after_filter/test_coverage.out
@@ -0,0 +1,6 @@
+Check [WILDCARD]/test.ts
+running 1 test from ./test.ts
+test ... ok ([WILDCARD])
+
+ok | 1 passed | 0 failed ([WILDCARD])
+