Feature/dependency injection (#38)

* fix markdown linting

* add dependency injection example

* update readme with di

* fix markdown code annotation

* fix readme

* one more readme fix

beginner/di/dependency_injection.go

@@ -0,0 +1,17 @@
+package di
+
+import (
+	"fmt"
+	"io"
+)
+
+// PrintCheckList to show D.I.
+//
+// dependency Injection makes testing easier
+// by creating functions that get all their
+// dependencies are arguments
+func PrintCheckList(writer io.Writer, list []string) {
+	for _, item := range list {
+		fmt.Fprintln(writer, item)
+	}
+}

beginner/di/dependency_injection_test.go

@@ -0,0 +1,30 @@
+package di
+
+import (
+	"bytes"
+	"testing"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestPrintCheckList(t *testing.T) {
+	Convey("Given a checklist", t, func() {
+		buffer := &bytes.Buffer{}
+		checklist := []string{
+			"[✓] Get milk",
+			"[✓] Learn Go",
+			"[✗] Book holidays",
+		}
+
+		PrintCheckList(buffer, checklist)
+
+		got := buffer.String()
+		want := `[✓] Get milk
+[✓] Learn Go
+[✗] Book holidays
+`
+		Convey("expect list items to be printed", func() {
+			So(got, ShouldEqual, want)
+		})
+	})
+}

go.mod

@@ -0,0 +1,7 @@
+module github.com/iampeterbanjo/golang-examples
+
+require (
+	github.com/jtolds/gls v4.2.1+incompatible // indirect
+	github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d // indirect
+	github.com/smartystreets/goconvey v0.0.0-20180222194500-ef6db91d284a
+)

go.sum

@@ -0,0 +1,6 @@
+github.com/jtolds/gls v4.2.1+incompatible h1:fSuqC+Gmlu6l/ZYAoZzx2pyucC8Xza35fpRVWLVmUEE=
+github.com/jtolds/gls v4.2.1+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
+github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d h1:zE9ykElWQ6/NYmHa3jpm/yHnI4xSofP+UP6SpjHcSeM=
+github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d/go.mod h1:OnSkiWE9lh6wB0YB77sQom3nweQdgAjqCqsofrRNTgc=
+github.com/smartystreets/goconvey v0.0.0-20180222194500-ef6db91d284a h1:JSvGDIbmil4Ui/dDdFBExb7/cmkNjyX5F97oglmvCDo=
+github.com/smartystreets/goconvey v0.0.0-20180222194500-ef6db91d284a/go.mod h1:XDJAKZRPZ1CvBcN2aX5YOUTYGHki24fSF0Iv48Ibg0s=