fix(doc): `deno doc --lint mod.ts` should output how many files checked (#21084)

As pointed out in https://github.com/denoland/deno/issues/21067 , it's
confusing that `deno doc --lint mod.ts` outputs the documentation to
stdout on success. Instead, it would be better if it outputted how many
files were checked similar to what `deno lint` does on success. It still
outputs the documentation if `--lint` or `--html` are provided so this
is non-breaking.

7 files changed, 94 insertions, 27 deletions

diff --git a/cli/tests/integration/doc_tests.rs b/cli/tests/integration/doc_tests.rs
index f5ac44a02..7a3f08f48 100644
--- a/cli/tests/integration/doc_tests.rs
+++ b/cli/tests/integration/doc_tests.rs
@@ -70,6 +70,23 @@ itest!(deno_doc_html_lint_referenced_private_types_fixed {
   output: "doc/referenced_private_types_lint.out",
 });
 
+itest!(deno_doc_lint_success {
+  args: "doc --lint doc/lint_success.ts",
+  output: "doc/lint_success.out",
+});
+
+itest!(deno_doc_lint_json_success {
+  args: "doc --lint --json doc/lint_success.ts",
+  output: "doc/lint_success_json.out",
+});
+
+itest!(deno_doc_lint_html_success {
+  args: "doc --lint --html --name=Library lint_success.ts",
+  copy_temp_dir: Some("doc"),
+  cwd: Some("doc"),
+  output: "doc/lint_success_html.out",
+});
+
 itest!(_060_deno_doc_displays_all_overloads_in_details_view {
   args:
     "doc --filter NS.test doc/060_deno_doc_displays_all_overloads_in_details_view.ts",
diff --git a/cli/tests/testdata/doc/lint_success.out b/cli/tests/testdata/doc/lint_success.out
new file mode 100644
index 000000000..c05ac45a1
--- /dev/null
+++ b/cli/tests/testdata/doc/lint_success.out
@@ -0,0 +1 @@
+Checked 1 file
diff --git a/cli/tests/testdata/doc/lint_success.ts b/cli/tests/testdata/doc/lint_success.ts
new file mode 100644
index 000000000..42c44b2d7
--- /dev/null
+++ b/cli/tests/testdata/doc/lint_success.ts
@@ -0,0 +1,5 @@
+/** My test class. */
+export class Test {
+  /** My property. */
+  prop: string;
+}
diff --git a/cli/tests/testdata/doc/lint_success_html.out b/cli/tests/testdata/doc/lint_success_html.out
new file mode 100644
index 000000000..8c4c2d187
--- /dev/null
+++ b/cli/tests/testdata/doc/lint_success_html.out
@@ -0,0 +1 @@
+Written 7 files to "./docs/"
diff --git a/cli/tests/testdata/doc/lint_success_json.out b/cli/tests/testdata/doc/lint_success_json.out
new file mode 100644
index 000000000..bf06a15cd
--- /dev/null
+++ b/cli/tests/testdata/doc/lint_success_json.out
@@ -0,0 +1,48 @@
+[
+  {
+    "kind": "class",
+    "name": "Test",
+    "location": {
+      "filename": "file:///[WILDCARD]/lint_success.ts",
+      "line": 2,
+      "col": 0
+    },
+    "declarationKind": "export",
+    "jsDoc": {
+      "doc": "My test class."
+    },
+    "classDef": {
+      "isAbstract": false,
+      "constructors": [],
+      "properties": [
+        {
+          "jsDoc": {
+            "doc": "My property."
+          },
+          "tsType": {
+            "repr": "string",
+            "kind": "keyword",
+            "keyword": "string"
+          },
+          "readonly": false,
+          "accessibility": null,
+          "optional": false,
+          "isAbstract": false,
+          "isStatic": false,
+          "name": "prop",
+          "location": {
+            "filename": "file:///[WILDCARD]/lint_success.ts",
+            "line": 4,
+            "col": 2
+          }
+        }
+      ],
+      "indexSignatures": [],
+      "methods": [],
+      "extends": null,
+      "implements": [],
+      "typeParams": [],
+      "superTypeParams": []
+    }
+  }
+]
diff --git a/cli/tests/testdata/doc/referenced_private_types_fixed.out b/cli/tests/testdata/doc/referenced_private_types_fixed.out
index 4621c6371..c05ac45a1 100644
--- a/cli/tests/testdata/doc/referenced_private_types_fixed.out
+++ b/cli/tests/testdata/doc/referenced_private_types_fixed.out
@@ -1,16 +1 @@
-Defined in file:///[WILDCARD]/referenced_private_types_fixed.ts:8:1
-
-class MyClass
-  Doc comment
-
-  prop: MyInterface
-    Doc comment
-
-Defined in file:///[WILDCARD]/referenced_private_types_fixed.ts:2:1
-
-interface MyInterface
-  Doc comment
-
-  prop?: string
-    Doc comment
-
+Checked 1 file
diff --git a/cli/tools/doc.rs b/cli/tools/doc.rs
index 9c88c8e84..75a559af1 100644
--- a/cli/tools/doc.rs
+++ b/cli/tools/doc.rs
@@ -138,9 +138,9 @@ pub async fn doc(flags: Flags, doc_flags: DocFlags) -> Result<(), AnyError> {
       let mut doc_nodes_by_url =
         IndexMap::with_capacity(module_specifiers.len());
 
-      for module_specifier in &module_specifiers {
-        let nodes = doc_parser.parse_with_reexports(module_specifier)?;
-        doc_nodes_by_url.insert(module_specifier.clone(), nodes);
+      for module_specifier in module_specifiers {
+        let nodes = doc_parser.parse_with_reexports(&module_specifier)?;
+        doc_nodes_by_url.insert(module_specifier, nodes);
       }
 
       if doc_flags.lint {
@@ -157,9 +157,23 @@ pub async fn doc(flags: Flags, doc_flags: DocFlags) -> Result<(), AnyError> {
       .boxed_local()
       .await
   } else {
-    let doc_nodes: Vec<doc::DocNode> =
-      doc_nodes_by_url.values().flatten().cloned().collect();
-    print_docs(doc_flags, doc_nodes)
+    let modules_len = doc_nodes_by_url.len();
+    let doc_nodes =
+      doc_nodes_by_url.into_values().flatten().collect::<Vec<_>>();
+
+    if doc_flags.json {
+      write_json_to_stdout(&doc_nodes)
+    } else if doc_flags.lint {
+      // don't output docs if running with only the --lint flag
+      log::info!(
+        "Checked {} file{}",
+        modules_len,
+        if modules_len == 1 { "" } else { "s" }
+      );
+      Ok(())
+    } else {
+      print_docs_to_stdout(doc_flags, doc_nodes)
+    }
   }
 }
 
@@ -204,14 +218,10 @@ async fn generate_docs_directory(
   Ok(())
 }
 
-fn print_docs(
+fn print_docs_to_stdout(
   doc_flags: DocFlags,
   mut doc_nodes: Vec<deno_doc::DocNode>,
 ) -> Result<(), AnyError> {
-  if doc_flags.json {
-    return write_json_to_stdout(&doc_nodes);
-  }
-
   doc_nodes.retain(|doc_node| doc_node.kind != doc::DocNodeKind::Import);
   let details = if let Some(filter) = doc_flags.filter {
     let nodes = doc::find_nodes_by_name_recursively(doc_nodes, filter.clone());