Improve test so that is passes.

The underlying maths for some statistics changed: ImageMagick/ImageMagick#6924 so the tests need to pass on both before and after maths.

bisect/bisect_analyze.sh

@@ -0,0 +1,61 @@
+#!/bin/sh
+
+
+#########################################################
+# How to run git bisect
+#########################################################
+
+## Check out ImageMagick
+# git clone https://github.com/ImageMagick/ImageMagick.git
+
+## Put a known good version of Imagick into the directory /var/app/bisect/ImageMagick/imagick
+
+## Update this script to run the relevant tests
+## e.g. change php run-tests.php tests/316_Imagick_getImageKurtosis.phpt
+
+## Start bisect session
+# git bisect start
+
+## Find bad version of ImageMagick e.g. a particular tag that is broken
+# git checkout 963f5fa
+
+## Mark that version as bad.
+# git bisect bad
+
+
+## Find a good version
+# git checkout 99da019
+
+## Mark that version as good.
+# git bisect good
+
+
+## Run the bisect automatically
+# git bisect run sh bisect_analyze.sh
+
+
+cd /var/app/bisect/ImageMagick
+
+./configure --with-quantum-depth=16 \
+  --disable-dependency-tracking \
+  --with-magick-plus-plus=no \
+  --without-perl \
+  --disable-docs \
+  --with-openexr=yes \
+  --with-fontconfig=yes \
+  --with-fftw \
+  --with-heic=yes \
+  --with-jpeg=yes \
+  --with-png=yes \
+  --with-tiff=yes \
+  --with-urw-base35-font-dir=/usr/share/fonts/type1/urw-base35 \
+  --with-webp=yes
+
+make clean
+make install -j20
+
+cd /var/app/bisect/ImageMagick/imagick
+phpize
+./configure
+make install
+php run-tests.php tests/316_Imagick_getImageKurtosis.phpt

tests/316_Imagick_getImageKurtosis.phpt

@@ -14,8 +14,16 @@ function getImageKurtosis() {
     $imagick = new \Imagick(__DIR__ . '/Biter_500.jpg');
     $values = $imagick->getImageKurtosis();
 
-    check_value($values, "kurtosis", -0.9379261035010518);
-    check_value($values, "skewness", 0.4562517200972045);
+    check_value_posibilities(
+        $values,
+        "kurtosis",
+        [-0.9379261035010518, -0.70925995674921]
+    );
+    check_value_posibilities(
+        $values,
+        "skewness",
+        [0.4562517200972045, 0.56839010636614]
+    );
 }
 
 getImageKurtosis() ;

tests/functions.inc

@@ -111,7 +111,10 @@ function setFontForImagickDraw(\ImagickDraw $imagickDraw)
     $imagickDraw->setFont($font);
 }
 
-
+/**
+ * Checks that a named value exists in an array and it matches
+ * an expected value.
+ */
 function check_value(array $values, $name, $expected_value)
 {
 	if (array_key_exists($name, $values) !== true) {
@@ -136,6 +139,41 @@ function check_value(array $values, $name, $expected_value)
 }
 
 
+/**
+ * Checks that a named value exists in an array and it matches
+ * one of a number of expected values.
+ * This function exists because the expected values for Kurtosis can
+ * change when the underlying maths changes: https://github.com/ImageMagick/ImageMagick/issues/6924
+ */
+function check_value_posibilities(array $values, $name, array $expected_values)
+{
+    if (array_key_exists($name, $values) !== true) {
+
+        $message = "Expected key '$name' not set. Array contains:\n";
+        $message .= var_export($values, true);
+
+        throw new \Exception($message);
+    }
+
+
+    $value = $values[$name];
+
+    $epsilon = 0.01;
+
+    foreach ($expected_values as $expected_value) {
+        if (($value > $expected_value - $epsilon) && ($value < $expected_value + $epsilon)) {
+            echo "Value for '$name' is $value which is close enough to expected $expected_value\n";
+            return;
+        }
+    }
+
+    $expected_string = implode(", ", $expected_values);
+
+    $message = "Value for $name doesn't match expected possibilities. Expected one of: $expected_string, actual: $value";
+    throw new \Exception($message);
+}
+
+
 function check_value_with_epsilon(array $values, $name, $expected_value, $epsilon)
 {
 	if (array_key_exists($name, $values) !== true) {