1 files changed, 211 insertions, 0 deletions
diff --git a/testing/modules/CoverageUtils.sys.mjs b/testing/modules/CoverageUtils.sys.mjs
new file mode 100644
index 0000000000..a19432305a
--- /dev/null
+++ b/testing/modules/CoverageUtils.sys.mjs
@@ -0,0 +1,211 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+import { addDebuggerToGlobal } from "resource://gre/modules/jsdebugger.sys.mjs";
+
+// eslint-disable-next-line mozilla/reject-globalThis-modification
+addDebuggerToGlobal(globalThis);
+
+/**
+ * Records coverage for each test by way of the js debugger.
+ */
+export var CoverageCollector = function (prefix) {
+  this._prefix = prefix;
+  this._dbg = new Debugger();
+  this._dbg.collectCoverageInfo = true;
+  this._dbg.addAllGlobalsAsDebuggees();
+  this._scripts = this._dbg.findScripts();
+
+  this._dbg.onNewScript = script => {
+    this._scripts.push(script);
+  };
+
+  // Source -> coverage data;
+  this._allCoverage = {};
+  this._encoder = new TextEncoder();
+
+  this._testIndex = 0;
+};
+
+CoverageCollector.prototype._getLinesCovered = function () {
+  let coveredLines = {};
+  let currentCoverage = {};
+  this._scripts.forEach(s => {
+    let scriptName = s.url;
+    let cov = s.getOffsetsCoverage();
+    if (!cov) {
+      return;
+    }
+
+    cov.forEach(covered => {
+      let { lineNumber, columnNumber, offset, count } = covered;
+      if (!count) {
+        return;
+      }
+
+      if (!currentCoverage[scriptName]) {
+        currentCoverage[scriptName] = {};
+      }
+      if (!this._allCoverage[scriptName]) {
+        this._allCoverage[scriptName] = {};
+      }
+
+      // NOTE: columnNumber is 1-origin.
+      let key = [lineNumber, columnNumber - 1, offset].join("#");
+      if (!currentCoverage[scriptName][key]) {
+        currentCoverage[scriptName][key] = count;
+      } else {
+        currentCoverage[scriptName][key] += count;
+      }
+    });
+  });
+
+  // Covered lines are determined by comparing every offset mentioned as of the
+  // the completion of a test to the last time we measured coverage. If an
+  // offset in a line is novel as of this test, or a count has increased for
+  // any offset on a particular line, that line must have been covered.
+  for (let scriptName in currentCoverage) {
+    for (let key in currentCoverage[scriptName]) {
+      if (
+        !this._allCoverage[scriptName] ||
+        !this._allCoverage[scriptName][key] ||
+        this._allCoverage[scriptName][key] < currentCoverage[scriptName][key]
+      ) {
+        // eslint-disable-next-line no-unused-vars
+        let [lineNumber, colNumber, offset] = key.split("#");
+        if (!coveredLines[scriptName]) {
+          coveredLines[scriptName] = new Set();
+        }
+        coveredLines[scriptName].add(parseInt(lineNumber, 10));
+        this._allCoverage[scriptName][key] = currentCoverage[scriptName][key];
+      }
+    }
+  }
+
+  return coveredLines;
+};
+
+CoverageCollector.prototype._getUncoveredLines = function () {
+  let uncoveredLines = {};
+  this._scripts.forEach(s => {
+    let scriptName = s.url;
+    let scriptOffsets = s.getAllOffsets();
+
+    if (!uncoveredLines[scriptName]) {
+      uncoveredLines[scriptName] = new Set();
+    }
+
+    // Get all lines in the script
+    scriptOffsets.forEach(function (element, index) {
+      if (!element) {
+        return;
+      }
+      uncoveredLines[scriptName].add(index);
+    });
+  });
+
+  // For all covered lines, delete their entry
+  for (let scriptName in this._allCoverage) {
+    for (let key in this._allCoverage[scriptName]) {
+      // eslint-disable-next-line no-unused-vars
+      let [lineNumber, columnNumber, offset] = key.split("#");
+      uncoveredLines[scriptName].delete(parseInt(lineNumber, 10));
+    }
+  }
+
+  return uncoveredLines;
+};
+
+CoverageCollector.prototype._getMethodNames = function () {
+  let methodNames = {};
+  this._scripts.forEach(s => {
+    let method = s.displayName;
+    // If the method name is undefined, we return early
+    if (!method) {
+      return;
+    }
+
+    let scriptName = s.url;
+    let tempMethodCov = [];
+    let scriptOffsets = s.getAllOffsets();
+
+    if (!methodNames[scriptName]) {
+      methodNames[scriptName] = {};
+    }
+
+    /**
+     * Get all lines contained within the method and
+     * push a record of the form:
+     * <method name> : <lines covered>
+     */
+    scriptOffsets.forEach(function (element, index) {
+      if (!element) {
+        return;
+      }
+      tempMethodCov.push(index);
+    });
+    methodNames[scriptName][method] = tempMethodCov;
+  });
+
+  return methodNames;
+};
+
+/**
+ * Records lines covered since the last time coverage was recorded,
+ * associating them with the given test name. The result is written
+ * to a json file in a specified directory.
+ */
+CoverageCollector.prototype.recordTestCoverage = function (testName) {
+  dump("Collecting coverage for: " + testName + "\n");
+  let rawLines = this._getLinesCovered(testName);
+  let methods = this._getMethodNames();
+  let uncoveredLines = this._getUncoveredLines();
+  let result = [];
+  let versionControlBlock = { version: 1.0 };
+  result.push(versionControlBlock);
+
+  for (let scriptName in rawLines) {
+    let rec = {
+      testUrl: testName,
+      sourceFile: scriptName,
+      methods: {},
+      covered: [],
+      uncovered: [],
+    };
+
+    if (
+      typeof methods[scriptName] != "undefined" &&
+      methods[scriptName] != null
+    ) {
+      for (let [methodName, methodLines] of Object.entries(
+        methods[scriptName]
+      )) {
+        rec.methods[methodName] = methodLines;
+      }
+    }
+
+    for (let line of rawLines[scriptName]) {
+      rec.covered.push(line);
+    }
+
+    for (let line of uncoveredLines[scriptName]) {
+      rec.uncovered.push(line);
+    }
+
+    result.push(rec);
+  }
+  let path = this._prefix + "/jscov_" + Date.now() + ".json";
+  dump("Writing coverage to: " + path + "\n");
+  return IOUtils.writeUTF8(path, JSON.stringify(result, undefined, 2), {
+    tmpPath: `${path}.tmp`,
+  });
+};
+
+/**
+ * Tear down the debugger after all tests are complete.
+ */
+CoverageCollector.prototype.finalize = function () {
+  this._dbg.removeAllDebuggees();
+  this._dbg.enabled = false;
+};