Lab1 - Generate Fibonacci Series

01_fib/jimbotech/README.md

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+# Fibonacci Number Generator
+## Overview
+As part of the ANZ "go" course the first lab is to produce a piece of software
+that will produce the Fibonacci series for fib(7).
+It was also an exercise in the tour.golang.org.
+
+Generating the series was implemented as "closure" which was a requirement in
+the tour-golang . There are other ways to solve this problem, 
+but I kept it as an example of closure for later reference.
+
+The function maintains state and hence has to be called sequentially.

01_fib/jimbotech/ex_fibonacci.go

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+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+var out io.Writer = os.Stdout
+
+// fibonacci returns a function that returns
+// an number in the fibonacci sequence.
+// This is an implmentation of "closure".
+// The inside function returns the current number
+// in the fibonnacci sequence, starting at 1
+// and sets up the next which will be returned
+// in the subsequent call
+func fibonacci() func() int {
+	secondLast, last := 0, 1
+
+	return func() int {
+		result := last
+		secondLast, last = last, secondLast+last
+		return result
+	}
+}
+
+func fibSeries(n int) []int {
+	counter := n
+	if n < 0 {
+		counter = -n
+	}
+	var fibSerial []int
+	f := fibonacci()
+	for i := 0; i < counter; i++ {
+		factor := 1
+		if n < 0 && i%2 != 0 {
+			factor = -1
+		}
+		fibSerial = append(fibSerial, f()*factor)
+	}
+	return fibSerial
+}
+
+func fib(n int) {
+	fibSer := fibSeries(n)
+	for _, v := range fibSer {
+		fmt.Fprintln(out, v)
+	}
+}
+
+func main() {
+	fib(7)
+}

01_fib/jimbotech/ex_fibonacci_test.go

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+package main
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestFib(t *testing.T) {
+
+	fibResults := []int{1, 1, 2, 3, 5, 8, 13, 21, 34}
+
+	f := fibonacci()
+
+	for _, val := range fibResults {
+		if r := f(); r != val {
+			t.Errorf("returned value %v does not match %v", r, val)
+		}
+	}
+}
+
+func TestMain(t *testing.T) {
+
+	want := "1\n1\n2\n3\n5\n8\n13\n"
+	var buf bytes.Buffer
+	out = &buf
+	main()
+	result := buf.String()
+
+	if result != want {
+		t.Errorf("expected %v, got %v", want, result)
+	}
+}
+
+func TestNeg(t *testing.T) {
+
+	want := "1\n-1\n2\n-3\n5\n-8\n13\n"
+	var buf bytes.Buffer
+	out = &buf
+	fib(-7)
+	result := buf.String()
+
+	if result != want {
+		t.Errorf("expected %v, got %v", want, result)
+	}
+}
+
+func TestZero(t *testing.T) {
+
+	var buf bytes.Buffer
+	out = &buf
+	fib(0)
+	result := buf.String()
+
+	if len(result) > 0 {
+		t.Errorf("expected nothing to be printed, got %v", result)
+	}
+}
+
+func TestOne(t *testing.T) {
+
+	want := "1\n"
+	var buf bytes.Buffer
+	out = &buf
+	fib(1)
+	result := buf.String()
+
+	if result != want {
+		t.Errorf("expected %v, got %v", want, result)
+	}
+}