Fix possible division by zero error

src/ProgressBar.php

@@ -31,6 +31,12 @@ final class ProgressBar
     /** Time when progress bar starts displaying  */
     private int $startTime;
 
+    /**
+     * Indicator whether maxProgress was truly set as zero.
+     * MaxProgress must always be at least one to be displayed.
+     */
+    private bool $maxProgressIsZero = false;
+
     /**
      * Initialize and set progress and maxProgress when available.
      * Use separate setProgress() and setMaxProgress() methods when undetermined during initialization.
@@ -204,7 +210,7 @@ private function setEstimatedTime(): ProgressBar
         $this->estimatedTime = round(
             (
                 time() - $this->startTime
-            ) / $this->progress * ($this->maxProgress - $this->progress)
+            ) / max(1, $this->progress) * ($this->maxProgress - $this->progress)
         );
 
         return $this;
@@ -215,6 +221,10 @@ private function setEstimatedTime(): ProgressBar
      */
     public function setMaxProgress(int|float $maxProgress): ProgressBar
     {
+        if ($maxProgress == 0) {
+            $this->maxProgressIsZero = true;
+        }
+
         $this->maxProgress = max(1, $maxProgress);
 
         return $this;
@@ -274,6 +284,12 @@ public function start(): void
      */
     public function tick(int $progress = 1): void
     {
+        if ($progress == 0 && $this->maxProgressIsZero) {
+            $this->finish();
+
+            return;
+        }
+
         $this->setProgress($this->progress + $progress)
             ->setEstimatedTime();
 

tests/ProgressBarTest.php

@@ -148,4 +148,18 @@ public function it_cannot_set_incorrect_max_progress()
 
         $this->assertEquals(1, $progressBar->getMaxProgress());
     }
+
+    /**
+     * @test
+     */
+    public function it_can_gracefully_handle_zero_progress()
+    {
+        $progressBar = new ProgressBar(maxProgress: 0);
+        $this->assertEquals(1, $progressBar->getMaxProgress());
+
+        $progressBar->tick(0);
+        $this->assertEquals(1, $progressBar->getProgress());
+
+        $this->assertEquals(100, $progressBar->getPercentage());
+    }
 }