diff --git a/.gitignore b/.gitignore
index 142affe..70336c6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 allFiredEvents
 scTopics
+scDebugLog
 coverage.json
 coverage/
 node_modules/
diff --git a/bin/exec.js b/bin/exec.js
index f005c34..93c1147 100644
--- a/bin/exec.js
+++ b/bin/exec.js
@@ -1,229 +1,20 @@
 #!/usr/bin/env node
-
-const shell = require('shelljs');
-const fs = require('fs');
+const App = require('./../lib/app.js');
 const reqCwd = require('req-cwd');
-const path = require('path');
-const childprocess = require('child_process');
-const istanbul = require('istanbul');
-const getInstrumentedVersion = require('./../lib/instrumentSolidity.js');
-const CoverageMap = require('./../lib/coverageMap.js');
-
-const istanbulCollector = new istanbul.Collector();
-const istanbulReporter = new istanbul.Reporter();
-
-// Very high gas block limits / contract deployment limits
-const gasLimitString = '0xfffffffffff';
-const gasLimitHex = 0xfffffffffff;
-const gasPriceHex = 0x01;
-
-const coverage = new CoverageMap();
-
-// Paths
-const coverageDir = './coverageEnv';        // Env that instrumented .sols are tested in
-
-// Options
-let coverageOption = '--network coverage';  // Default truffle network execution flag
-let silence = '';                           // Default log level: configurable by --silence
-let log = console.log;
-
-let testrpcProcess;                         // ref to testrpc server we need to close on exit
-let events;                                 // ref to string loaded from 'allFiredEvents'
-let testsErrored = null;                    // flag set to non-null if truffle tests error
+const death = require('death');
+const log = console.log;
 
-// --------------------------------------- Utilities -----------------------------------------------
-/**
- * Removes coverage build artifacts, kills testrpc.
- * Exits (1) and prints msg on error, exits (0) otherwise.
- * @param  {String} err error message
- */
-function cleanUp(err) {
-  log('Cleaning up...');
-  shell.config.silent = true;
-  shell.rm('-Rf', `${coverageDir}`);
-  shell.rm('./allFiredEvents');
-  shell.rm('./scTopics');
-  if (testrpcProcess) { testrpcProcess.kill(); }
-
-  if (err) {
-    log(`${err}\nExiting without generating coverage...`);
-    process.exit(1);
-  } else if (testsErrored) {
-    log('Some truffle tests failed while running coverage');
-    process.exit(1);
-  } else {
-    process.exit(0);
-  }
-}
-// --------------------------------------- Script --------------------------------------------------
 const config = reqCwd.silent('./.solcover.js') || {};
+const app = new App(config);
 
-const workingDir = config.dir || '.';       // Relative path to contracts folder
-let port = config.port || 8555;             // Port testrpc listens on
-const accounts = config.accounts || 35;     // Number of accounts to testrpc launches with
-const copyNodeModules = config.copyNodeModules || false; // Whether we copy node_modules when making coverage environment
-let skipFiles = config.skipFiles || []; // Which files should be skipped during instrumentation
-
-// Silence shell and script logging (for solcover's unit tests / CI)
-if (config.silent) {
-  silence = '> /dev/null 2>&1';
-  log = () => {};
-}
-
-// Generate a copy of the target project configured for solcover and save to the coverage
-// environment folder.
-log('Generating coverage environment');
-try {
-  let files = shell.ls(workingDir);
-  const nmIndex = files.indexOf('node_modules');
-
-  if (!config.copyNodeModules && nmIndex > -1) {
-    files.splice(nmIndex, 1); // Removes node_modules from array.
-  }
-
-  files = files.map(file => `${workingDir}/` + file);
-  shell.mkdir(coverageDir);
-  shell.cp('-R', files, coverageDir);
-
-  const truffleConfig = reqCwd.silent(`${workingDir}/truffle.js`);
-
-  // Coverage network opts specified: use port if declared
-  if (truffleConfig && truffleConfig.networks && truffleConfig.networks.coverage) {
-    port = truffleConfig.networks.coverage.port || port;
-
-  // Coverage network opts NOT specified: default to the development network w/ modified
-  // port, gasLimit, gasPrice. Export the config object only.
-  } else {
-    const trufflejs = `
-      module.exports = {
-        networks: {
-          development: {
-            host: "localhost",
-            network_id: "*",
-            port: ${port},
-            gas: ${gasLimitHex},
-            gasPrice: ${gasPriceHex}
-          }
-        }
-      };`;
-
-    coverageOption = '';
-    fs.writeFileSync(`${coverageDir}/truffle.js`, trufflejs);
-  }
-} catch (err) {
-  const msg = ('There was a problem generating the coverage environment: ');
-  cleanUp(msg + err);
-}
-
-// For each contract except migrations.sol (or those in skipFiles):
-// 1. Generate file path reference for coverage report
-// 2. Load contract as string
-// 3. Instrument contract
-// 4. Save instrumented contract in the coverage environment folder where covered tests will run
-// 5. Add instrumentation info to the coverage map
-skipFiles = skipFiles.map(contract => `${coverageDir}/contracts/` + contract);
-skipFiles.push(`${coverageDir}/contracts/Migrations.sol`);
-
-let currentFile;
-try {
-  shell.ls(`${coverageDir}/contracts/**/*.sol`).forEach(file => {
-    if (!skipFiles.includes(file)) {
-      log('Instrumenting ', file);
-      currentFile = file;
-
-      const contractPath = path.resolve(file);
-      const canonicalPath = contractPath.split('/coverageEnv').join('');
-      const contract = fs.readFileSync(contractPath).toString();
-      const instrumentedContractInfo = getInstrumentedVersion(contract, canonicalPath);
-      fs.writeFileSync(contractPath, instrumentedContractInfo.contract);
-      coverage.addContract(instrumentedContractInfo, canonicalPath);
-    } else {
-      log('Skipping instrumentation of ', file);
-    }
-  });
-} catch (err) {
-  const msg = (`There was a problem instrumenting ${currentFile}: `);
-  cleanUp(msg + err);
-}
-
-new Promise((resolve, reject) => {
-  // Run modified testrpc with large block limit, on (hopefully) unused port.
-  // (Changes here should be also be added to the before() block of test/run.js).
-  if (!config.norpc) {
-    const defaultRpcOptions = `--gasLimit ${gasLimitString} --accounts ${accounts} --port ${port}`;
-    const testrpcOptions = config.testrpcOptions || defaultRpcOptions;
-    const command = './node_modules/ethereumjs-testrpc-sc/bin/testrpc ';
-
-    testrpcProcess = childprocess.exec(command + testrpcOptions, null, (err, stdout, stderr) => {
-      if (err) {
-        if(stdout) log(`testRpc stdout:\n${stdout}`);
-        if(stderr) log(`testRpc stderr:\n${stderr}`);
-        cleanUp('testRpc errored after launching as a childprocess.');
-      }
-    });
-    testrpcProcess.stdout.on('data', data => {
-      if (data.includes('Listening')) {
-        log(`Launched testrpc on port ${port}`);
-        return resolve();
-      }
-    });
-  } else {
-    return resolve();
-  }
-}).then(() => {
-  // Run truffle (or config.testCommand) over instrumented contracts in the
-  // coverage environment folder. Shell cd command needs to be invoked
-  // as its own statement for command line options to work, apparently.
-  try {
-    log('Launching test command (this can take a few seconds)...');
-    const defaultCommand = `truffle test ${coverageOption} ${silence}`;
-    const command = config.testCommand || defaultCommand;
-    shell.cd('./coverageEnv');
-    shell.exec(command);
-    testsErrored = shell.error();
-    shell.cd('./..');
-  } catch (err) {
-    cleanUp(err);
-  }
-
-  // Get events fired during instrumented contracts execution.
-  try {
-    events = fs.readFileSync('./allFiredEvents').toString().split('\n');
-    events.pop();
-  } catch (err) {
-    const msg =
-    `
-      There was an error generating coverage. Possible reasons include:
-      1. Another application is using port ${port}
-      2. Truffle crashed because your tests errored
-
-    `;
-    cleanUp(msg + err);
-  }
-
-  // Generate coverage / write coverage report / run istanbul
-  try {
-    coverage.generate(events, './contracts');
-
-    const json = JSON.stringify(coverage.coverage);
-    fs.writeFileSync('./coverage.json', json);
+app.generateCoverageEnvironment();
+app.instrumentTarget();
+app.launchTestrpc()
+  .then(() => {
+    app.runTestCommand();
+    app.generateReport();
+  })
+  .catch(err => log(err));
 
-    istanbulCollector.add(coverage.coverage);
-    istanbulReporter.add('html');
-    istanbulReporter.add('lcov');
-    istanbulReporter.add('text');
-    istanbulReporter.write(istanbulCollector, true, () => {
-      log('Istanbul coverage reports generated');
-    });
-  } catch (err) {
-    if (config.testing) {
-      cleanUp();
-    } else {
-      const msg = 'There was a problem generating producing the coverage map / running Istanbul.\n';
-      cleanUp(msg + err);
-    }
-  }
+death((signal, err) => app.cleanUp(err));
 
-  // Finish
-  cleanUp();
-});
diff --git a/circle.yml b/circle.yml
index 10befe7..07cf94c 100644
--- a/circle.yml
+++ b/circle.yml
@@ -1,6 +1,9 @@
 machine:
   node:
     version: 6.11.0
+dependencies:
+  override:
+    - npm install
 test:
   override:
     - npm run test-cov
diff --git a/lib/app.js b/lib/app.js
new file mode 100644
index 0000000..9f66ad7
--- /dev/null
+++ b/lib/app.js
@@ -0,0 +1,266 @@
+const shell = require('shelljs');
+const fs = require('fs');
+const path = require('path');
+const childprocess = require('child_process');
+const reqCwd = require('req-cwd');
+const istanbul = require('istanbul');
+const getInstrumentedVersion = require('./instrumentSolidity.js');
+const CoverageMap = require('./coverageMap.js');
+const defaultTruffleConfig = require('./truffleConfig.js');
+
+const gasLimitHex = 0xfffffffffff;               // High gas block limit / contract deployment limit
+const gasPriceHex = 0x01;                        // Low gas price
+
+/**
+ * Coverage Runner
+ */
+class App {
+  constructor(config){
+    this.coverageDir = './coverageEnv';          // Env that instrumented .sols are tested in
+
+    // Options
+    this.network = '';                           // Default truffle network execution flag
+    this.silence = '';                           // Default log level: configurable by --silence
+    this.log = console.log;
+
+    // Other
+    this.testrpcProcess;                         // ref to testrpc server we need to close on exit
+    this.events;                                 // ref to string loaded from 'allFiredEvents'
+    this.testsErrored = null;                    // flag set to non-null if truffle tests error
+    this.coverage = new CoverageMap();           // initialize a coverage map
+    
+    // Config
+    this.config = config || {};
+    this.workingDir = config.dir || '.';         // Relative path to contracts folder
+    this.accounts = config.accounts || 35;       // Number of accounts to testrpc launches with
+    this.skipFiles = config.skipFiles || [];     // Which files should be skipped during instrumentation
+    this.norpc = config.norpc || false;          // Launch testrpc-sc internally?
+    this.port = config.port || 8555;             // Port testrpc should listen on
+    
+    this.copyNodeModules = config.copyNodeModules || false;  // Copy node modules into coverageEnv?
+    this.testrpcOptions = config.testrpcOptions || null;     // Options for testrpc-sc
+    this.testCommand = config.testCommand || null;           // Optional test command
+
+    this.setLoggingLevel(config.silent);
+  }
+
+  //--------------------------------------  Methods ------------------------------------------------
+  
+  /**
+   * Generates a copy of the target project configured for solidity-coverage and saves to 
+   * the coverage environment folder. Process exits(1) if try fails
+  */
+  generateCoverageEnvironment(){
+
+    this.log('Generating coverage environment');
+    
+    try {
+      let files = shell.ls(this.workingDir);
+      const nmIndex = files.indexOf('node_modules');
+
+      // Removes node_modules from array (unless requested).
+      if (!this.copyNodeModules && nmIndex > -1) {
+        files.splice(nmIndex, 1); 
+      }
+
+      files = files.map(file => `${this.workingDir}/${file}`);
+      shell.mkdir(this.coverageDir);
+      shell.cp('-R', files, this.coverageDir);
+
+      const truffleConfig = reqCwd.silent(`${this.workingDir}/truffle.js`);
+
+      // Coverage network opts specified: use port if declared
+      if (truffleConfig && truffleConfig.networks && truffleConfig.networks.coverage) {
+        this.port = truffleConfig.networks.coverage.port || this.port;
+        this.network = '--network coverage';
+      
+      // No coverage network defaults to the dev network on port 8555, high gas / low price. 
+      } else {
+        const trufflejs = defaultTruffleConfig(this.port, gasLimitHex, gasPriceHex)
+        fs.writeFileSync(`${this.coverageDir}/truffle.js`, trufflejs);
+      }
+    } catch (err) {
+      const msg = ('There was a problem generating the coverage environment: ');
+      this.cleanUp(msg + err);
+    }
+  }
+
+  /**
+   * For each contract except migrations.sol (or those in skipFiles):
+   * + Generate file path reference for coverage report
+   * + Load contract as string
+   * + Instrument contract
+   * + Save instrumented contract in the coverage environment folder where covered tests will run
+   * + Add instrumentation info to the coverage map
+   */
+  instrumentTarget(){
+
+    this.skipFiles = this.skipFiles.map(contract => `${this.coverageDir}/contracts/${contract}`);
+    this.skipFiles.push(`${this.coverageDir}/contracts/Migrations.sol`);
+
+    let currentFile;
+    try {
+      shell.ls(`${this.coverageDir}/contracts/**/*.sol`).forEach(file => {
+        if (!this.skipFiles.includes(file)) {
+          this.log('Instrumenting ', file);
+          currentFile = file;
+
+          const contractPath = path.resolve(file);
+          const canonicalPath = contractPath.split(this.coverageDir).join('');
+          const contract = fs.readFileSync(contractPath).toString();
+          const instrumentedContractInfo = getInstrumentedVersion(contract, canonicalPath);
+          fs.writeFileSync(contractPath, instrumentedContractInfo.contract);
+          this.coverage.addContract(instrumentedContractInfo, canonicalPath);
+        } else {
+          this.log('Skipping instrumentation of ', file);
+        }
+      });
+    } catch (err) {
+      const msg = `There was a problem instrumenting ${currentFile}: `;
+      this.cleanUp(msg + err);
+    }
+  }
+
+  /**
+   *  Run modified testrpc with large block limit, on (hopefully) unused port.
+   *  Changes here should be also be added to the before() block of test/run.js).
+   *  @return {Promise} Resolves when testrpc prints 'Listening' to std out / norpc is true.
+   */
+  launchTestrpc(){
+    return new Promise((resolve, reject) => {
+    
+      if (!this.norpc) {
+        const defaultRpcOptions = `--gasLimit ${gasLimitHex} --accounts ${this.accounts} --port ${this.port}`;
+        const options = this.testrpcOptions || defaultRpcOptions;
+        const command = './node_modules/ethereumjs-testrpc-sc/bin/testrpc ';
+
+        // Launch
+        this.testrpcProcess = childprocess.exec(command + options, null, (err, stdout, stderr) => {
+          if (err) {
+            if(stdout) this.log(`testRpc stdout:\n${stdout}`);
+            if(stderr) this.log(`testRpc stderr:\n${stderr}`);
+            this.cleanUp('testRpc errored after launching as a childprocess.');
+          }
+        });
+
+        // Resolve when testrpc logs that it's listening. 
+        this.testrpcProcess.stdout.on('data', data => {
+          if (data.includes('Listening')) {
+            this.log(`Launched testrpc on port ${this.port}`);
+            return resolve();
+          }
+        });
+      } else {
+        return resolve();
+      }
+    })
+  }
+
+  /**
+   *  Run truffle (or config.testCommand) over instrumented contracts in the
+   *  coverage environment folder. Shell cd command needs to be invoked
+   *  as its own statement for command line options to work, apparently.
+   *  Also reads the 'allFiredEvents' log.
+   */
+  runTestCommand(){
+   
+    try {
+      
+      const defaultCommand = `truffle test ${this.network} ${this.silence}`;
+      const command = this.testCommand || defaultCommand;
+      this.log(`Running: ${command}\n(this can take a few seconds)...`);
+      shell.cd(this.coverageDir);
+      shell.exec(command);
+      this.testsErrored = shell.error();
+      shell.cd('./..');
+    } catch (err) {
+      this.cleanUp(err);
+    }
+
+    // Get events fired during instrumented contracts execution.
+    try {
+      this.events = fs.readFileSync('./allFiredEvents').toString().split('\n');
+      this.events.pop();
+    } catch (err) {
+      const msg =
+      `
+        There was an error generating coverage. Possible reasons include:
+        1. Another application is using port ${this.port}
+        2. Truffle crashed because your tests errored
+
+      `;
+      this.cleanUp(msg + err);
+    }
+  }
+
+  /**
+   * Generate coverage / write coverage report / run istanbul
+   */
+  generateReport(){
+
+    const collector = new istanbul.Collector();
+    const reporter = new istanbul.Reporter();
+
+    return new Promise((resolve, reject) => {
+      try {
+        this.coverage.generate(this.events, './contracts');
+
+        const json = JSON.stringify(this.coverage.coverage);
+        fs.writeFileSync('./coverage.json', json);
+
+        collector.add(this.coverage.coverage);
+        reporter.add('html');
+        reporter.add('lcov');
+        reporter.add('text');
+        reporter.write(collector, true, () => {
+          this.log('Istanbul coverage reports generated');
+          this.cleanUp();
+          resolve();
+        });
+      } catch (err) {
+          const msg = 'There was a problem generating the coverage map / running Istanbul.\n';
+          this.cleanUp(msg + err);
+
+      }
+    })
+  }
+
+  // ------------------------------------------ Utils ----------------------------------------------
+  
+  /**
+   * Allows config to turn logging off (for CI)
+   * @param {Boolean} isSilent 
+   */
+  setLoggingLevel(isSilent){
+    if (isSilent) {
+      this.silence = '> /dev/null 2>&1';
+      this.log = () => {};
+    }
+  }
+
+  /**
+   * Removes coverage build artifacts, kills testrpc.
+   * Exits (1) and prints msg on error, exits (0) otherwise.
+   * @param  {String} err error message
+   */
+  cleanUp(err) {
+    this.log('Cleaning up...');
+    shell.config.silent = true;
+    shell.rm('-Rf', this.coverageDir);
+    shell.rm('./allFiredEvents');
+    shell.rm('./scTopics');
+    if (this.testrpcProcess) { this.testrpcProcess.kill(); }
+
+    if (err) {
+      this.log(`${err}\nExiting without generating coverage...`);
+      process.exit(1);
+    } else if (this.testsErrored) {
+      this.log('Some truffle tests failed while running coverage');
+      process.exit(1);
+    } else {
+      process.exit(0);
+    }
+  }
+}
+
+module.exports = App;
diff --git a/lib/coverageMap.js b/lib/coverageMap.js
index 6f9d191..813c891 100644
--- a/lib/coverageMap.js
+++ b/lib/coverageMap.js
@@ -75,10 +75,8 @@ module.exports = class CoverageMap {
     this.branchTopics.push(branchHash);
     this.statementTopics.push(statementHash);
 
-    fs.appendFileSync('./scTopics', `${lineHash}\n`);
-    fs.appendFileSync('./scTopics', `${fnHash}\n`);
-    fs.appendFileSync('./scTopics', `${branchHash}\n`);
-    fs.appendFileSync('./scTopics', `${statementHash}\n`);
+    const topics = `${lineHash}\n${fnHash}\n${branchHash}\n${statementHash}\n`;
+    fs.appendFileSync('./scTopics', topics);
   }
 
   /**
diff --git a/lib/truffleConfig.js b/lib/truffleConfig.js
new file mode 100644
index 0000000..e1bb15c
--- /dev/null
+++ b/lib/truffleConfig.js
@@ -0,0 +1,14 @@
+module.exports = function truffleConfig(port, gasLimit, gasPrice) {
+    return `
+      module.exports = {
+        networks: {
+          development: {
+            host: "localhost",
+            network_id: "*",
+            port: ${port},
+            gas: ${gasLimit},
+            gasPrice: ${gasPrice}
+          }
+        }
+      };`
+};
\ No newline at end of file
diff --git a/package.json b/package.json
index 473d82a..deb8117 100644
--- a/package.json
+++ b/package.json
@@ -22,6 +22,7 @@
   "license": "ISC",
   "dependencies": {
     "commander": "^2.9.0",
+    "death": "^1.1.0",
     "ethereumjs-testrpc-sc": "https://github.com/sc-forks/testrpc-sc.git",
     "istanbul": "^0.4.5",
     "keccakjs": "^0.2.1",
@@ -44,6 +45,6 @@
     "merkle-patricia-tree": "~2.1.2",
     "mocha": "^3.1.0",
     "solc": "0.4.8",
-    "truffle": "3.2.5"
+    "truffle": "3.4.4"
   }
 }
diff --git a/test/cli.js b/test/app.js
similarity index 99%
rename from test/cli.js
rename to test/app.js
index 2dd53e2..fb2e80e 100644
--- a/test/cli.js
+++ b/test/app.js
@@ -14,7 +14,7 @@ function collectGarbage() {
   if (global.gc) { global.gc(); }
 }
 
-describe('cli', () => {
+describe('app', () => {
   let testrpcProcess = null;
   const script = 'node ./bin/exec.js';
   const port = 8555;