Add right margin when menu is shrunk

src/Exception/CannotShrinkMenuException.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpSchool\CliMenu\Exception;
+
+use InvalidArgumentException;
+
+class CannotShrinkMenuException extends InvalidArgumentException
+{
+    public static function fromMarginAndTerminalWidth(int $margin, int $terminalWidth) : self
+    {
+        return new self(
+            sprintf(
+                'Cannot shrink menu. Margin: %s * 2 with terminal width: %s leaves no space for menu',
+                $margin,
+                $terminalWidth
+            )
+        );
+    }
+}

src/MenuStyle.php

@@ -2,6 +2,7 @@
 
 namespace PhpSchool\CliMenu;
 
+use PhpSchool\CliMenu\Exception\CannotShrinkMenuException;
 use PhpSchool\CliMenu\Terminal\TerminalFactory;
 use PhpSchool\CliMenu\Util\ColourUtil;
 use PhpSchool\CliMenu\Util\StringUtil as s;
@@ -400,11 +401,11 @@ public function setWidth(int $width) : self
         Assertion::greaterOrEqualThan($width, 0);
 
         $this->requestedWidth = $width;
-        $width = $this->maybeShrinkWidth($this->margin, $width);
 
-        $this->width = $width;
+        $this->width = $this->maybeShrinkWidth($this->marginAuto ? 0 : $this->margin, $width);
+
         if ($this->marginAuto) {
-            $this->calculateMarginAuto($width);
+            $this->calculateMarginAuto($this->width);
         }
 
         $this->calculateContentWidth();
@@ -416,8 +417,12 @@ public function setWidth(int $width) : self
 
     private function maybeShrinkWidth(int $margin, int $width) : int
     {
-        if ($width + $margin >= $this->terminal->getWidth()) {
-            $width = $this->terminal->getWidth() - $margin;
+        if ($width + ($margin * 2) >= $this->terminal->getWidth()) {
+            $width = $this->terminal->getWidth() - ($margin * 2);
+
+            if ($width <= 0) {
+                throw CannotShrinkMenuException::fromMarginAndTerminalWidth($margin, $this->terminal->getWidth());
+            }
         }
 
         return $width;

test/Builder/CliMenuBuilderTest.php

@@ -774,7 +774,13 @@ public function marginBelowZeroProvider() : array
      */
     public function testSetMarginAcceptsZeroAndPositiveIntegers(int $value) : void
     {
-        $menu = (new CliMenuBuilder)->setMargin($value)->build();
+        $terminal = self::createMock(Terminal::class);
+        $terminal
+            ->expects($this->any())
+            ->method('getWidth')
+            ->will($this->returnValue(200));
+
+        $menu = (new CliMenuBuilder($terminal))->setMargin($value)->build();
 
         self::assertSame($value, $menu->getStyle()->getMargin());
     }

test/CliMenuTest.php

@@ -40,7 +40,7 @@ public function setUp() : void
 
         $this->terminal->expects($this->any())
             ->method('getWidth')
-            ->willReturn(46);
+            ->willReturn(48);
 
         $this->terminal->expects($this->any())
             ->method('write')

test/Dialogue/ConfirmTest.php

@@ -35,7 +35,7 @@ public function setUp() : void
 
         $this->terminal->expects($this->any())
             ->method('getWidth')
-            ->willReturn(46);
+            ->willReturn(48);
 
         $this->terminal->expects($this->any())
             ->method('write')

test/Dialogue/FlashTest.php

@@ -35,7 +35,7 @@ public function setUp() : void
 
         $this->terminal->expects($this->any())
             ->method('getWidth')
-            ->willReturn(46);
+            ->willReturn(48);
 
         $this->terminal->expects($this->any())
             ->method('write')

test/Exception/CannotShrinkMenuExceptionTest.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpSchool\CliMenuTest\Exception;
+
+use PhpSchool\CliMenu\Exception\CannotShrinkMenuException;
+use PHPUnit\Framework\TestCase;
+
+class CannotShrinkMenuExceptionTest extends TestCase
+{
+    public function testException() : void
+    {
+        $e = CannotShrinkMenuException::fromMarginAndTerminalWidth(10, 15);
+        $this->assertEquals(
+            'Cannot shrink menu. Margin: 10 * 2 with terminal width: 15 leaves no space for menu',
+            $e->getMessage()
+        );
+    }
+}

test/MenuStyleTest.php

@@ -3,6 +3,7 @@
 namespace PhpSchool\CliMenuTest;
 
 use PhpSchool\CliMenu\Builder\CliMenuBuilder;
+use PhpSchool\CliMenu\Exception\CannotShrinkMenuException;
 use PhpSchool\CliMenu\Exception\InvalidInstantiationException;
 use PhpSchool\CliMenu\MenuStyle;
 use PhpSchool\Terminal\UnixTerminal;
@@ -313,11 +314,11 @@ public function testSetMarginWhenWidthIsLargerThanTerminal() : void
         $style->setMargin(20);
 
         self::assertSame(20, $style->getMargin());
-        self::assertSame(480, $style->getWidth());
+        self::assertSame(460, $style->getWidth());
 
         $style->setMargin(35);
         self::assertSame(35, $style->getMargin());
-        self::assertSame(465, $style->getWidth());
+        self::assertSame(430, $style->getWidth());
     }
 
     public function testMarginAutoCenters() : void
@@ -712,4 +713,24 @@ public function testDebugMode() : void
             $style->getBorderTopRows()
         );
     }
+
+    /**
+     * @dataProvider cannotShrinkProvider
+     */
+    public function testSetWidthThrowsExceptionIfMenuTooWideAndMarginConsumesTerminal(int $margin) : void
+    {
+        $this->expectException(CannotShrinkMenuException::class);
+        $this->expectExceptionMessage(
+            "Cannot shrink menu. Margin: $margin * 2 with terminal width: 100 leaves no space for menu"
+        );
+
+        $style = $this->getMenuStyle(8, 100);
+        $style->setMargin($margin);
+        $style->setWidth(10);
+    }
+
+    public function cannotShrinkProvider() : array
+    {
+        return [[50], [51], [100]];
+    }
 }

test/res/testSimpleOpenCloseWithMarginAutoAndBorders.txt

@@ -1,11 +1,11 @@
 
 
-                                      
-                                      
-            PHP School FTW            
-            ======================    
-            ● Item 1                  
-                                      
-                                      
+                                       
+                                       
+             PHP School FTW            
+             ======================    
+             ● Item 1                  
+                                       
+