Add tests for HorizonPrometheusExporter and our Custom Exporters (#1105)

Add some simple tests. These instantiate the existing exporters and
check that their collection method works. Another test instantiates the
exporter repository with our application config to check it is valid

Bug: T423429
Co-authored-by: Ollie <43674967+outdooracorn@users.noreply.github.com>

Author: tarrow

tests/HorizonPrometheusExporter/ExporterRepositoryTest.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace Tests\HorizonPrometheusExporter;
+
+use LKDevelopment\HorizonPrometheusExporter\Repository\ExporterRepository;
+use Prometheus\CollectorRegistry;
+use Tests\TestCase;
+
+class ExporterRepositoryTest extends TestCase {
+    public function testCanBeCreated() {
+        // if nothing is passed to load(), exporters are read from the config at config/horizon-exporter.php
+        ExporterRepository::load();
+        $registry = ExporterRepository::getRegistry();
+        $this->assertInstanceOf(CollectorRegistry::class, $registry);
+    }
+}

tests/Metrics/FailedQsBatchesTest.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Tests\Metrics;
+
+use App\Metrics\FailedQsBatches;
+use LKDevelopment\HorizonPrometheusExporter\Repository\ExporterRepository;
+use Tests\TestCase;
+
+class FailedQsBatchesTest extends TestCase {
+    public function testCanBeCreated() {
+        ExporterRepository::load([FailedQsBatches::class]);
+
+        self::assertNotNull(ExporterRepository::getRegistry());
+
+        $gauge = ExporterRepository::getRegistry()->getGauge(config('horizon-exporter.namespace'), 'qs_batches_failed_batches');
+
+        self::assertNotNull($gauge);
+
+    }
+}

tests/Metrics/PendingQsBatchesTest.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace Tests\Metrics;
+
+use App\Metrics\PendingQsBatches;
+use LKDevelopment\HorizonPrometheusExporter\Repository\ExporterRepository;
+use Tests\TestCase;
+
+class PendingQsBatchesTest extends TestCase {
+    public function testCanBeCreated() {
+        ExporterRepository::load([PendingQsBatches::class]);
+
+        self::assertNotNull(ExporterRepository::getRegistry());
+
+        $gauge = ExporterRepository::getRegistry()->getGauge(config('horizon-exporter.namespace'), 'qs_batches_pending_batches');
+
+        self::assertNotNull($gauge);
+    }
+}

tests/Metrics/WikiEntityImportsTest.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace Tests\Metrics;
+
+use App\Metrics\WikiEntityImports;
+use LKDevelopment\HorizonPrometheusExporter\Repository\ExporterRepository;
+use Tests\TestCase;
+
+class WikiEntityImportsTest extends TestCase {
+    public function testCanBeCreated() {
+        ExporterRepository::load([WikiEntityImports::class]);
+
+        self::assertNotNull(ExporterRepository::getRegistry());
+
+        $gauge = ExporterRepository::getRegistry()->getGauge(config('horizon-exporter.namespace'), 'wiki_entity_imports_pending');
+
+        self::assertNotNull($gauge);
+    }
+}