2 files changed, 25 insertions, 2 deletions
diff --git a/cli/args/flags.rs b/cli/args/flags.rs
index 9feef54b0..f47d5b121 100644
--- a/cli/args/flags.rs
+++ b/cli/args/flags.rs
@@ -162,6 +162,12 @@ pub struct RunFlags {
   pub script: String,
 }
 
+impl RunFlags {
+  pub fn is_stdin(&self) -> bool {
+    self.script == "-"
+  }
+}
+
 #[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
 pub struct TaskFlags {
   pub cwd: Option<String>,
diff --git a/cli/args/mod.rs b/cli/args/mod.rs
index ecbc53db7..85e44aca2 100644
--- a/cli/args/mod.rs
+++ b/cli/args/mod.rs
@@ -278,8 +278,25 @@ impl CliOptions {
     self.flags.compat
   }
 
-  pub fn coverage_dir(&self) -> Option<&String> {
-    self.flags.coverage_dir.as_ref()
+  pub fn coverage_dir(&self) -> Option<String> {
+    fn allow_coverage(sub_command: &DenoSubcommand) -> bool {
+      match sub_command {
+        DenoSubcommand::Test(_) => true,
+        DenoSubcommand::Run(flags) => !flags.is_stdin(),
+        _ => false,
+      }
+    }
+
+    if allow_coverage(self.sub_command()) {
+      self
+        .flags
+        .coverage_dir
+        .as_ref()
+        .map(ToOwned::to_owned)
+        .or_else(|| env::var("DENO_UNSTABLE_COVERAGE_DIR").ok())
+    } else {
+      None
+    }
   }
 
   pub fn enable_testing_features(&self) -> bool {