add unit tests for doesMQMatch()

Author: tilomitra

index.js

@@ -6,12 +6,13 @@ See the accompanying LICENSE file for terms.
 
 'use strict';
 
-module.exports = match;
+module.exports = matchMQ;
 
 // -----------------------------------------------------------------------------
 
-function match(mediaQuery, values) {
-    return parseQuery(mediaQuery);
+function matchMQ(mediaQuery, values) {
+    //return parseQuery(mediaQuery);
+    return doesMQMatch(mediaQuery, values);
 }
 
 // -- Utilities ----------------------------------------------------------------
@@ -91,3 +92,158 @@ function toPx(length) {
         default   : return value;
     }
 }
+
+function toDecimal(ratio) {
+    var numbers = ratio.match(/^(\d+)\s*\/\s*(\d+)$/);
+    return numbers[1] / numbers[2];
+}
+
+function doesMQMatch(mq, query) {
+
+    //get the AST
+    var parsed = parseQuery(mq),
+        didMQMatch = true;
+
+    parsed.forEach(function (p) {
+        p.expressions.forEach(function (e) {
+            //if the query contains this property, then we need to do a check to see if it passes the threshold. If any of the matches are false, then the media query does not pass.
+            var match = checkForMatch(e, query);
+            if (!match) {
+                didMQMatch = false;
+            }
+        });
+    });
+
+    return didMQMatch;
+}
+
+function checkForMatch (exp, query) {
+    var val = query[exp.property],
+        isMatch = false;
+
+    //if there's a value for this property, then we need to see if it is within the threshold
+    //doing an explicit undefined check here so that `0` goes through.
+    if (val !== undefined) {
+        switch (exp.property) {
+            case 'device-width':
+            case 'device-height':
+            case 'width':
+            case 'height':
+                isMatch = doesLengthPass(exp, val);
+                break;
+
+            case 'color':
+            case 'color-index':
+            case 'monochrome':
+                isMatch = doesColorPass(exp, val);
+                break;
+
+            case 'resolution':
+                isMatch = doesResolutionPass(exp, val);
+                break;
+
+            case 'aspect-ratio':
+                isMatch = doesAspectRatioPass(exp, val);
+                break;
+
+            case 'orientation':
+            case 'scan':
+                isMatch = doesScanPass(exp, val);
+                break;
+
+            case 'grid':
+                isMatch = doesGridPass(exp, val);
+                break;
+
+        }
+
+        return isMatch;
+    }
+
+    //if there is not a value for the property, then we can return true.
+    else {
+        return true;
+    }
+}
+
+function checkMinMax (expVal, queryVal, modifier) {
+    switch (modifier) {
+        case 'min':
+            //if the value we want is greater than the minimum required, then it's true.
+            if (expVal <= queryVal) {
+                return true;
+            }
+            break;
+        case 'max':
+            //if the value we want is less than or equal to the maximum required, then it's true.
+            if (expVal >= queryVal) {
+                return true;
+            }
+            break;
+        default:
+            //sometimes we may not have a modifier. in this case, the value has to be an exact match.
+            if (expVal === queryVal) {
+                return true;
+            }
+            break;
+    }
+
+    return false;
+}
+
+function doesTypePass (parsed, value) {
+    var type = (value instanceof 'string') ? value : 'object'
+    if (parsed === value) {
+        return true;
+    }
+    else {
+        return false;
+    }
+}
+
+function doesLengthPass (exp, val) {
+    var expToPx = toPx(exp.value),
+        valToPx = toPx(val);
+
+    return checkMinMax(expToPx, valToPx, exp.modifier);
+}
+
+function doesColorPass (exp, val) {
+    var expInt;
+
+    //this is the (min-width: foo) and (color) use case, which means "any colored device"
+    if (!exp.value) {
+        if (val === 0) return false;
+        else return true;
+    }
+
+    //assigning after exp.value `undefined` check.
+    expInt = parseInt(exp.value);
+    return checkMinMax(expInt, val, exp.modifier);
+
+}
+
+function doesResolutionPass (exp, val) {
+    var expDpi = toDpi(exp.value),
+        valDpi = (typeof val === 'string') ? toDpi(val) : val;
+
+    return checkMinMax(expDpi, valDpi, exp.modifier);
+}
+
+function doesAspectRatioPass (exp, val) {
+    var expDec = toDecimal(exp.value),
+        valDec = (typeof val === 'string') ? toDecimal(val) : val;
+    return checkMinMax(expDec, valDec, exp.modifier);
+}
+
+function doesScanPass (exp, val) {
+    if (exp.value === val) {
+        return true;
+    }
+    return false;
+}
+
+function doesGridPass (exp, val) {
+    //the only way grid would return false is if we explicitly had {grid: <falsy val>} in our query object.
+    return !!val;
+}

package.json

@@ -4,7 +4,7 @@
   "description": "Determines if a given CSS Media Query matches a set of values.",
   "main": "index.js",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "node_modules/.bin/mocha"
   },
   "repository": {
     "type": "git",
@@ -22,5 +22,9 @@
   "bugs": {
     "url": "https://github.com/ericf/css-media-match/issues"
   },
-  "homepage": "https://github.com/ericf/css-media-match"
+  "homepage": "https://github.com/ericf/css-media-match",
+  "devDependencies": {
+    "mocha": "~1.16.2",
+    "chai": "~1.8.1"
+  }
 }