add export test:

- make requests to the testbed container for 'svg', 'pdf' and 'eps'
  image formats.
- test that those request return non-empty images

Author: etpinard

test/image/export_test.js

@@ -0,0 +1,105 @@
+var fs = require('fs');
+var path = require('path');
+
+var request = require('request');
+var test = require('tape');
+
+var constants = require('../../tasks/util/constants');
+var getOptions = require('../../tasks/util/get_image_request_options');
+
+var userFileName = process.argv[2];
+
+/**
+ * Image formats to test
+ *
+ * N.B. 'png' is tested in `compare_pixels_test.js`
+ *
+ * TODO figure why 'jpeg' and 'webp' lead to errors
+ *
+ */
+var FORMATS = ['svg', 'pdf', 'eps'];
+
+/**
+ * The tests below determine whether the images are properly
+ * exported by (only) checking the file size of the generated images.
+ *
+ * MIN_SIZE is the minimum satisfactory file size.
+ */
+var MIN_SIZE = 100;
+
+
+// make artifact folder
+if(!fs.existsSync(constants.pathToTestImages)) {
+    fs.mkdirSync(constants.pathToTestImages);
+}
+
+if(!userFileName) runAll();
+else {
+
+    if(path.extname(userFileName) !== '.json') {
+        throw new Error('user-specified mock must end with \'.json\'');
+    }
+
+    runSingle(userFileName);
+}
+
+function runAll() {
+    test('testing export formats', function(t) {
+
+        // non-exhaustive list of mocks to test
+        var fileNames = [
+            '0.json',
+            'geo_first.json',
+            'gl3d_z-range.json'
+        ];
+
+        t.plan(fileNames.length * FORMATS.length);
+
+        fileNames.forEach(function(fileName) {
+            testExports(fileName, t);
+        });
+    });
+}
+
+function runSingle(userFileName) {
+    test('testing export for: ' + userFileName, function(t) {
+        t.plan(FORMATS.length);
+
+        testExports(userFileName, t);
+    });
+}
+
+function testExports(fileName, t) {
+    FORMATS.forEach(function(format) {
+        testExport(fileName, format, t);
+    });
+}
+
+function testExport(fileName, format, t) {
+    var figure = require(path.join(constants.pathToTestImageMocks, fileName));
+    var bodyMock = {
+        figure: figure,
+        format: format,
+        scale: 1
+    };
+
+    var imageFileName = fileName.split('.')[0] + '.' + format;
+    var savedImagePath = path.join(constants.pathToTestImages, imageFileName);
+    var savedImageStream = fs.createWriteStream(savedImagePath);
+
+    var options = getOptions(bodyMock, 'http://localhost:9010/');
+
+    function checkExport(err) {
+        if(err) throw err;
+
+        fs.stat(savedImagePath, function(err, stats) {
+            var didExport = stats.size > MIN_SIZE;
+
+            t.ok(didExport, imageFileName + ' should be properly exported');
+        });
+    }
+
+    request(options)
+        .pipe(savedImageStream)
+        .on('close', checkExport);
+}