Merge pull request #502 from phpmetrics/fix/501

Manage better description inference for stable dependencies principle.

Author: niconoe-

src/Hal/Violation/Package/StableDependenciesPrinciple.php

@@ -60,9 +60,12 @@ public function getLevel(): int
 
     public function getDescription(): string
     {
-        $count = count($this->violatingInstabilities);
-        /** @var float $instability */
         $instability = $this->metric->getInstability();
+        if (null === $instability) {
+            return 'Packages should depend in the direction of stability.';
+        }
+
+        $count = count($this->violatingInstabilities);
         $thisInstability = round($instability, 3);
         $packages = implode(
             "\n* ",

tests/Violation/Package/StableDependenciesPrincipleTest.php

@@ -40,6 +40,13 @@ public static function provideMetricToCheckIfViolationApplies(): Generator
     {
         yield 'Invalid metric' => [Phake::mock(Metric::class), Phake::mock(ViolationsHandlerInterface::class), false];
 
+        $violationsHandler = Phake::mock(ViolationsHandlerInterface::class);
+        $packageMetric = Phake::mock(PackageMetric::class);
+        Phake::when($packageMetric)->__call('get', ['violations'])->thenReturn($violationsHandler);
+        Phake::when($packageMetric)->__call('getInstability', [])->thenReturn(null);
+        Phake::when($packageMetric)->__call('getDependentInstabilities', [])->thenReturn([]);
+        yield 'Instability not defined' => [$packageMetric, $violationsHandler, false];
+
         $violationsHandler = Phake::mock(ViolationsHandlerInterface::class);
         $packageMetric = Phake::mock(PackageMetric::class);
         Phake::when($packageMetric)->__call('get', ['violations'])->thenReturn($violationsHandler);
@@ -113,6 +120,14 @@ public function testViolationApplies(
         Phake::verify($violationsHandler)->__call('add', [$violation]);
         Phake::verifyNoOtherInteractions($violationsHandler);
         $instability = $metric->getInstability();
+
+        if (null === $instability) {
+            $expectedDescription = 'Packages should depend in the direction of stability.';
+            self::assertSame($expectedDescription, $violation->getDescription());
+            return;
+        }
+        /** @var int $violatingInstabilities the inference */
+
         $violatingInstabilities = array_filter(
             $metric->getDependentInstabilities(),
             static fn (float $otherInstability): bool => $otherInstability >= $instability