Test Observable.reduce;

tests/observable.lua

@@ -166,4 +166,5 @@ describe('Observable', function()
   dofile('tests/merge.lua')
   dofile('tests/pack.lua')
   dofile('tests/pluck.lua')
+  dofile('tests/reduce.lua')
 end)

tests/reduce.lua

@@ -0,0 +1,36 @@
+describe('reduce', function()
+  it('fails if the first argument is not a function', function()
+    local observable = Rx.Observable.fromValue(0)
+    expect(observable:reduce()).to.fail()
+    expect(observable:reduce(1)).to.fail()
+    expect(observable:reduce('')).to.fail()
+    expect(observable:reduce({})).to.fail()
+    expect(observable:reduce(true)).to.fail()
+  end)
+
+  it('uses the seed as the initial value to the accumulator', function()
+    local accumulator = spy()
+    Rx.Observable.fromValue(3):reduce(accumulator, 4):subscribe()
+    expect(accumulator[1]).to.equal({4, 3})
+  end)
+
+  it('waits for 2 values before accumulating if the seed is nil', function()
+    local accumulator = spy(function(x, y) return x * y end)
+    local observable = Rx.Observable.fromTable({2, 4, 6}, ipairs):reduce(accumulator)
+    expect(observable).to.produce(48)
+    expect(accumulator).to.equal({{2, 4}, {8, 6}})
+  end)
+
+  it('uses the return value of the accumulator as the next input to the accumulator', function()
+    local accumulator = spy(function(x, y) return x + y end)
+    local observable = Rx.Observable.fromTable({1, 2, 3}, ipairs):reduce(accumulator, 0)
+    expect(observable).to.produce(6)
+    expect(accumulator).to.equal({{0, 1}, {1, 2}, {3, 3}})
+  end)
+
+  it('passes all produced values to the accumulator', function()
+    local accumulator = spy(function() return 0 end)
+    local observable = Rx.Observable.fromTable({2, 3, 4}, ipairs, true):reduce(accumulator, 0):subscribe()
+    expect(accumulator).to.equal({{0, 2, 1}, {0, 3, 2}, {0, 4, 3}})
+  end)
+end)