Add unit tests for compositecache and stagebuilder

* add mock types for testing
* enhance error messaging
* add tests

pkg/executor/composite_cache_test.go

@@ -0,0 +1,121 @@
+package executor
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"reflect"
+	"testing"
+)
+
+func Test_NewCompositeCache(t *testing.T) {
+	r := NewCompositeCache()
+	if reflect.TypeOf(r).String() != "*executor.CompositeCache" {
+		t.Errorf("expected return to be *executor.CompositeCache but was %v", reflect.TypeOf(r).String())
+	}
+}
+
+func Test_CompositeCache_AddKey(t *testing.T) {
+	keys := []string{
+		"meow",
+		"purr",
+	}
+	r := NewCompositeCache()
+	r.AddKey(keys...)
+	if len(r.keys) != 2 {
+		t.Errorf("expected keys to have length 2 but was %v", len(r.keys))
+	}
+}
+
+func Test_CompositeCache_Key(t *testing.T) {
+	r := NewCompositeCache("meow", "purr")
+	k := r.Key()
+	if k != "meow-purr" {
+		t.Errorf("expected result to equal meow-purr but was %v", k)
+	}
+}
+
+func Test_CompositeCache_Hash(t *testing.T) {
+	r := NewCompositeCache("meow", "purr")
+	h, err := r.Hash()
+	if err != nil {
+		t.Errorf("expected error to be nil but was %v", err)
+	}
+
+	expectedHash := "b4fd5a11af812a11a79d794007c842794cc668c8e7ebaba6d1e6d021b8e06c71"
+	if h != expectedHash {
+		t.Errorf("expected result to equal %v but was %v", expectedHash, h)
+	}
+}
+
+func Test_CompositeCache_AddPath_dir(t *testing.T) {
+	tmpDir, err := ioutil.TempDir("/tmp", "foo")
+	if err != nil {
+		t.Errorf("got error setting up test %v", err)
+	}
+
+	content := `meow meow meow`
+	if err := ioutil.WriteFile(filepath.Join(tmpDir, "foo.txt"), []byte(content), 0777); err != nil {
+		t.Errorf("got error writing temp file %v", err)
+	}
+
+	fn := func() string {
+		r := NewCompositeCache()
+		if err := r.AddPath(tmpDir); err != nil {
+			t.Errorf("expected error to be nil but was %v", err)
+		}
+
+		if len(r.keys) != 1 {
+			t.Errorf("expected len of keys to be 1 but was %v", len(r.keys))
+		}
+		hash, err := r.Hash()
+		if err != nil {
+			t.Errorf("couldnt generate hash from test cache")
+		}
+		return hash
+	}
+
+	hash1 := fn()
+	hash2 := fn()
+	if hash1 != hash2 {
+		t.Errorf("expected hash %v to equal hash %v", hash1, hash2)
+	}
+}
+func Test_CompositeCache_AddPath_file(t *testing.T) {
+	tmpfile, err := ioutil.TempFile("/tmp", "foo.txt")
+	if err != nil {
+		t.Errorf("got error setting up test %v", err)
+	}
+	defer os.Remove(tmpfile.Name()) // clean up
+
+	content := `meow meow meow`
+	if _, err := tmpfile.Write([]byte(content)); err != nil {
+		t.Errorf("got error writing temp file %v", err)
+	}
+	if err := tmpfile.Close(); err != nil {
+		t.Errorf("got error closing temp file %v", err)
+	}
+
+	p := tmpfile.Name()
+	fn := func() string {
+		r := NewCompositeCache()
+		if err := r.AddPath(p); err != nil {
+			t.Errorf("expected error to be nil but was %v", err)
+		}
+
+		if len(r.keys) != 1 {
+			t.Errorf("expected len of keys to be 1 but was %v", len(r.keys))
+		}
+		hash, err := r.Hash()
+		if err != nil {
+			t.Errorf("couldnt generate hash from test cache")
+		}
+		return hash
+	}
+
+	hash1 := fn()
+	hash2 := fn()
+	if hash1 != hash2 {
+		t.Errorf("expected hash %v to equal hash %v", hash1, hash2)
+	}
+}