MDL-44725 Availability: Add utility API to make unit testing easier (7)

Previously there was no way in PHP to create the JSON values used for
availability, except by manually hard-coding them (the main code to
do this normally is in JavaScript).

This makes unit tests hard to read, so I have implemented static
functions tree::get_root_json and tree::get_nested_json which allow
for easier-to-read unit tests.

availability/classes/tree.php

@@ -621,4 +621,99 @@ class tree extends tree_node {
         }
         return $changed;
     }
+
+    /**
+     * Returns a JSON object which corresponds to a tree.
+     *
+     * Intended for unit testing, as normally the JSON values are constructed
+     * by JavaScript code.
+     *
+     * This function generates 'nested' (i.e. not root-level) trees.
+     *
+     * @param array $children Array of JSON objects from component children
+     * @param string $op Operator (tree::OP_xx)
+     * @return stdClass JSON object
+     * @throws coding_exception If you get parameters wrong
+     */
+    public static function get_nested_json(array $children, $op = self::OP_AND) {
+
+        // Check $op and work out its type.
+        switch($op) {
+            case self::OP_AND:
+            case self::OP_NOT_OR:
+            case self::OP_OR:
+            case self::OP_NOT_AND:
+                break;
+            default:
+                throw new \coding_exception('Invalid $op');
+        }
+
+        // Do simple tree.
+        $result = new \stdClass();
+        $result->op = $op;
+        $result->c = $children;
+        return $result;
+    }
+
+    /**
+     * Returns a JSON object which corresponds to a tree at root level.
+     *
+     * Intended for unit testing, as normally the JSON values are constructed
+     * by JavaScript code.
+     *
+     * The $show parameter can be a boolean for all OP_xx options. For OP_AND
+     * and OP_NOT_OR where you have individual show options, you can specify
+     * a boolean (same for all) or an array.
+     *
+     * @param array $children Array of JSON objects from component children
+     * @param string $op Operator (tree::OP_xx)
+     * @param bool|array $show Whether 'show' option is turned on (see above)
+     * @return stdClass JSON object ready for encoding
+     * @throws coding_exception If you get parameters wrong
+     */
+    public static function get_root_json(array $children, $op = self::OP_AND, $show = true) {
+
+        // Get the basic object.
+        $result = self::get_nested_json($children, $op);
+
+        // Check $op type.
+        switch($op) {
+            case self::OP_AND:
+            case self::OP_NOT_OR:
+                $multishow = true;
+                break;
+            case self::OP_OR:
+            case self::OP_NOT_AND:
+                $multishow = false;
+                break;
+        }
+
+        // Add show options depending on operator.
+        if ($multishow) {
+            if (is_bool($show)) {
+                $result->showc = array_pad(array(), count($result->c), $show);
+            } else if (is_array($show)) {
+                // The JSON will break if anything isn't an actual bool, so check.
+                foreach ($show as $item) {
+                    if (!is_bool($item)) {
+                        throw new \coding_exception('$show array members must be bool');
+                    }
+                }
+                // Check the size matches.
+                if (count($show) != count($result->c)) {
+                    throw new \coding_exception('$show array size does not match $children');
+                }
+                $result->showc = $show;
+            } else {
+                throw new \coding_exception('$show must be bool or array');
+            }
+        } else {
+            if (!is_bool($show)) {
+                throw new \coding_exception('For this operator, $show must be bool');
+            }
+            $result->show = $show;
+        }
+
+        return $result;
+    }
 }