[Ethereum] Failed to install Truffle on MacOS Mojave

Why don't you simply run npm install -g truffle to install truffle,, with TestRPC as your Ethereum client, you can install TestRPC using the command npm install -g ethereumjs-testrpc

It worked for me this way

The origin of the issue is because you're trying to deploy the contract from the file migrations/1_initial_migration.js that is supposed to be used only for the deployment of Migration.sol.

To deploy your contracts, you need to create a file in migrations/2_deploy_contracts.js that contains the deployment part of TestCrowsale.sol

migrations/1_initial_migration.js

var Migrations = artifacts.require("./Migrations.sol");
module.exports = function(deployer) {
   deployer.deploy(Migrations);
};

migrations/2_deploy_contracts.js

var TestCrowdsale = artifacts.require("./TestCrowdsale.sol");

module.exports = function(deployer) {
   deployTestCrowdsale(deployer);
};

function deployTestCrowdsale(deployer) {

   const accounts = web3.eth.accounts;

   const startTime = latestTime();
   const endTime = startTime + duration.days(45);
   const rate = 2500;
   const goal = web3.toWei(250, 'ether');
   const cap = web3.toWei(4000, 'ether');
   const wallet = accounts[0];

   return deployer.deploy(TestCrowdsale, startTime, endTime, rate, wallet);

}

function latestTime() {
  return web3.eth.getBlock('latest').timestamp;
}

const duration = {
   seconds: function (val) { return val; },
   minutes: function (val) { return val * this.seconds(60); },
   hours: function (val) { return val * this.minutes(60); },
   days: function (val) { return val * this.hours(24); },
   weeks: function (val) { return val * this.days(7); },
   years: function (val) { return val * this.days(365); },
};

I tried on my side and the deployment go through :

Compiling ./contracts/Migrations.sol...
Writing artifacts to ./build/contracts

Using network 'development'.

Running migration: 1_initial_migration.js
  Deploying Migrations...
  ... 0x46dd08a7e00419adc52c3b9b048f89812dd960463b02125a93eb7e43eb4ca64f
  Migrations: 0x4a5a1448d37aeaaae79deed7e0d3f81ebc52db87
Saving successful migration to network...
  ... 0x573964afa1f79deca003871bd793026f7c932d9c46b8be055184e10790a63147
Saving artifacts...
Running migration: 2_deploy_contracts.js
  Deploying TestCrowdsale...
  ... 0xd251d1b3b92facb64e38ce3e04907197e9b7b9e7fefdf083da1b43c08f1b9bb1
  TestCrowdsale: 0xd817d9295491556f00a45c8092e42c10df271865
Saving successful migration to network...
  ... 0x83a2ba140f54003fc0f146ff2d8b8e2f6d9013122d59d94a39a74d4a9c8df92e
Saving artifacts..

I pushed the code here for more details: https://github.com/gjeanmart/stackexchange/tree/master/36690-error-encountered-bailing-network-state-unknown-review-successful-transaction