fix examples (#699)

Examples are broken for

1. all functions
2. any class in a namespace
3. any examples without code (.md only)

This fixes all of it, and adds a test.

Author: jjergus

composer.lock

@@ -18,19 +18,20 @@
 final class Examples extends PageSection {
   <<__Override>>
   public function getMarkdown(): ?string {
-    $path = LocalConfig::ROOT.'/api-examples/';
     if ($this->parent !== null) {
-      $path .= 'class.'.$this->parent->getName().'/';
+      $subdirectory = 'class.'.$this->parent->getName().'/';
     } else {
-      $path .= 'function';
+      $subdirectory = 'function.';
     }
-    $path .= Str\replace(
-      $this->definition->getName(),
-      "\\",
-      '.',
+    $subdirectory .= $this->definition->getName();
+
+    $path = Str\format(
+      '%s/api-examples/%s',
+      LocalConfig::ROOT,
+      Str\replace($subdirectory, '\\', '.'),
     );
 
-    $examples = Vec\concat(\glob($path.'/*.php'), \glob($path.'/*.php'))
+    $examples = Vec\concat(\glob($path.'/*.md'), \glob($path.'/*.php'))
       |> Vec\map($$, $file ==> \pathinfo($file, \PATHINFO_FILENAME))
       |> keyset($$);
 

src/hh-apidoc-extensions/PageSections/Examples.php

@@ -6,11 +6,12 @@
   APIDefinitionType,
   APINavData,
   APIProduct,
+  LocalConfig,
   NavDataNode,
   URLBuilder,
 };
 
-use namespace HH\Lib\Vec;
+use namespace HH\Lib\{Str, Vec};
 use function Facebook\FBExpect\expect;
 use type Facebook\HackTest\{DataProvider, TestGroup};
 
@@ -177,4 +178,28 @@ public function getDoNotDocument(): vec<(string, APIDefinitionType)> {
       \sprintf('"%s" should not be documented', $name),
     );
   }
+
+  public function getPagesWithExamples(): vec<vec<string>> {
+    $root = LocalConfig::ROOT.'/api-examples';
+    $urls = keyset[];
+    foreach (\glob($root.'/class.*/*') as $dir) {
+      if (!\is_dir($dir)) {
+        continue;
+      }
+      $urls[] = Str\replace($dir, $root.'/class.', 'class/');
+    }
+    foreach (\glob($root.'/function.*') as $dir) {
+      $urls[] = Str\replace($dir, $root.'/function.', 'function/');
+    }
+    return Vec\map($urls, $url ==> vec['/hack/reference/'.$url.'/']);
+  }
+
+  <<DataProvider('getPagesWithExamples')>>
+  public async function testExamples(string $url): Awaitable<void> {
+    list($response, $body) = await PageLoader::getPageAsync($url);
+    expect($response->getStatusCode())
+      ->toBeSame(200, 'Examples provided for non-existent page %s.', $url);
+    expect(Str\contains($body, '<a href="#examples">'))
+      ->toBeTrue('Missing examples at %s.', $url);
+  }
 }