feat(All): check that all stream items satisfy condition

Author: sharpvik

all.go

@@ -0,0 +1,10 @@
+package fungi
+
+// All returns true if and only if all stream items satisfy given condition.
+func All[T any](pass func(T) bool) StreamReducer[T, bool] {
+	return func(item Stream[T]) (ok bool, err error) {
+		fail, err := Any(func(item T) bool { return !pass(item) })(item)
+		ok = !fail
+		return
+	}
+}

all_test.go

@@ -0,0 +1,24 @@
+package fungi
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAllTrue(t *testing.T) {
+	source := SliceStream([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10})
+	justOddNumbers := Filter(odd)
+	allNumbersAreOdd := All(odd)
+	result, err := allNumbersAreOdd(justOddNumbers(source))
+	assert.NoError(t, err)
+	assert.True(t, result)
+}
+
+func TestAllFalse(t *testing.T) {
+	source := SliceStream([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10})
+	allNumbersAreEven := All(even)
+	result, err := allNumbersAreEven(source)
+	assert.NoError(t, err)
+	assert.False(t, result)
+}