test(filter): add filter tests from RxJS legacy

Add most RxJS legacy tests. Just 3 tests are missing still, which are
related to test helpers not yet available in RxJS Next.

Author: Andre Medeiros

spec/operators/filter-spec.js

@@ -7,13 +7,170 @@ describe('Observable.prototype.filter()', function () {
     return (+x) % 2 === 1;
   }
 
+  function isPrime(i) {
+    if (+i <= 1) { return false; }
+    var max = Math.floor(Math.sqrt(+i));
+    for (var j = 2; j <= max; ++j) {
+      if (+i % j === 0) { return false; }
+    }
+    return true;
+  }
+
   it('should filter out even values', function () {
     var source = hot('--0--1--2--3--4--|');
     var expected =   '-----1-----3-----|';
 
     expectObservable(source.filter(oddFilter)).toBe(expected);
   });
 
+  it('should filter in only prime numbers', function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--|');
+    var expected =          '--3---5----7-------|';
+
+    expectObservable(source.filter(isPrime)).toBe(expected);
+  });
+
+  it('should filter with an always-true predicate', function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--|');
+    var expected =          '--3-4-5-6--7-8--9--|';
+    var predicate = function () { return true; };
+
+    expectObservable(source.filter(predicate)).toBe(expected);
+  });
+
+  it('should filter with an always-false predicate', function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--|');
+    var expected =          '-------------------|';
+    var predicate = function () { return false; };
+
+    expectObservable(source.filter(predicate)).toBe(expected);
+  });
+
+  it('should filter in only prime numbers, source unsubscribes early', function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--|');
+    var unsub =             '------------!';
+    var expected =          '--3---5----7-';
+
+    expectObservable(source.filter(isPrime), unsub).toBe(expected);
+  });
+
+  it('should filter in only prime numbers, source throws', function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--#');
+    var expected =          '--3---5----7-------#';
+
+    expectObservable(source.filter(isPrime)).toBe(expected);
+  });
+
+  it('should filter in only prime numbers, but predicate throws', function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--|');
+    var expected =          '--3---5-#';
+
+    var invoked = 0;
+    var predicate = function (x) {
+      invoked++;
+      if (invoked === 4) {
+        throw 'error';
+      }
+      return isPrime(x);
+    };
+
+    expectObservable(source.filter(predicate)).toBe(expected);
+  });
+
+  it('should filter in only prime numbers, predicate with index', function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--|');
+    var expected =          '--3--------7-------|';
+
+    var predicate = function (x, i) {
+      return isPrime((+x) + i * 10);
+    };
+
+    expectObservable(source.filter(predicate)).toBe(expected);
+  });
+
+  it('should filter in only prime numbers, predicate with index, ' +
+    'source unsubscribes early',
+  function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--|');
+    var unsub =             '------------!';
+    var expected =          '--3--------7-';
+
+    var predicate = function (x, i) {
+      return isPrime((+x) + i * 10);
+    };
+
+    expectObservable(source.filter(predicate), unsub).toBe(expected);
+  });
+
+  it('should filter in only prime numbers, predicate with index, source throws', function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--#');
+    var expected =          '--3--------7-------#';
+
+    var predicate = function (x, i) {
+      return isPrime((+x) + i * 10);
+    };
+
+    expectObservable(source.filter(predicate)).toBe(expected);
+  });
+
+  it('should filter in only prime numbers, predicate with index and throws', function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--|');
+    var expected =          '--3-----#';
+
+    var invoked = 0;
+    var predicate = function (x, i) {
+      invoked++;
+      if (invoked === 4) {
+        throw 'error';
+      }
+      return isPrime((+x) + i * 10);
+    };
+
+    expectObservable(source.filter(predicate)).toBe(expected);
+  });
+
+  it('should compose with another filter to allow multiples of six', function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--|');
+    var expected =          '--------6----------|';
+
+    expectObservable(
+      source
+        .filter(function (x) { return x % 2 === 0; })
+        .filter(function (x) { return x % 3 === 0; })
+    ).toBe(expected);
+  });
+
+  it('should be able to accept and use a thisArg', function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--|');
+    var expected =          '--------6----------|';
+
+    function Filterer() {
+      this.filter1 = function (x) { return x % 2 === 0; };
+      this.filter2 = function (x) { return x % 3 === 0; };
+    }
+
+    var filterer = new Filterer();
+
+    expectObservable(
+      source
+        .filter(function (x) { return this.filter1(x); }, filterer)
+        .filter(function (x) { return this.filter2(x); }, filterer)
+        .filter(function (x) { return this.filter1(x); }, filterer)
+    ).toBe(expected);
+  });
+
+  it('should be able to use filter and map composed', function () {
+    var source = hot('-1--2--^-3-4-5-6--7-8--9--|');
+    var expected =          '----a---b----c-----|';
+    var values = { a: 16, b: 36, c: 64 };
+
+    expectObservable(
+      source
+        .filter(function (x) { return x % 2 === 0; })
+        .map(function (x) { return x * x; })
+    ).toBe(expected, values);
+  });
+
   it('should propagate errors from the source', function () {
     var source = hot('--0--1--2--3--4--#');
     var expected =   '-----1-----3-----#';