Better validation and test coverage for background colours

lib/colour.js

@@ -83,18 +83,22 @@ function toColorspace (colorspace) {
  * Update a colour attribute of the this.options Object.
  * @private
  * @param {String} key
- * @param {String|Object} val
- * @throws {Error} Invalid key
+ * @param {String|Object} value
+ * @throws {Error} Invalid value
  */
-function _setColourOption (key, val) {
-  if (is.object(val) || is.string(val)) {
-    const colour = color(val);
-    this.options[key] = [
-      colour.red(),
-      colour.green(),
-      colour.blue(),
-      Math.round(colour.alpha() * 255)
-    ];
+function _setBackgroundColourOption (key, value) {
+  if (is.defined(value)) {
+    if (is.object(value) || is.string(value)) {
+      const colour = color(value);
+      this.options[key] = [
+        colour.red(),
+        colour.green(),
+        colour.blue(),
+        Math.round(colour.alpha() * 255)
+      ];
+    } else {
+      throw is.invalidParameterError('background', 'object or string', value);
+    }
   }
 }
 
@@ -111,7 +115,7 @@ module.exports = function (Sharp) {
     toColourspace,
     toColorspace,
     // Private
-    _setColourOption
+    _setBackgroundColourOption
   });
   // Class attributes
   Sharp.colourspace = colourspace;

lib/operation.js

@@ -179,7 +179,7 @@ function blur (sigma) {
 function flatten (options) {
   this.options.flatten = is.bool(options) ? options : true;
   if (is.object(options)) {
-    this._setColourOption('flattenBackground', options.background);
+    this._setBackgroundColourOption('flattenBackground', options.background);
   }
   return this;
 }

lib/platform.js

@@ -7,6 +7,7 @@ const env = process.env;
 module.exports = function () {
   const arch = env.npm_config_arch || process.arch;
   const platform = env.npm_config_platform || process.platform;
+  /* istanbul ignore next */
   const libc = (platform === 'linux' && detectLibc.isNonGlibcLinux) ? detectLibc.family : '';
 
   const platformId = [`${platform}${libc}`];

lib/resize.js

@@ -239,7 +239,7 @@ function resize (width, height, options) {
     }
     // Background
     if (is.defined(options.background)) {
-      this._setColourOption('resizeBackground', options.background);
+      this._setBackgroundColourOption('resizeBackground', options.background);
     }
     // Kernel
     if (is.defined(options.kernel)) {
@@ -305,7 +305,7 @@ function extend (extend) {
     this.options.extendBottom = extend.bottom;
     this.options.extendLeft = extend.left;
     this.options.extendRight = extend.right;
-    this._setColourOption('extendBackground', extend.background);
+    this._setBackgroundColourOption('extendBackground', extend.background);
   } else {
     throw is.invalidParameterError('extend', 'integer or object', extend);
   }