add multi which can return multiple resources

5 files changed, 134 insertions, 10 deletions

diff --git a/internal/resource/multi.go b/internal/resource/multi.go
new file mode 100644
index 0000000..1694814
--- /dev/null
+++ b/internal/resource/multi.go
@@ -0,0 +1,39 @@
+package resource
+
+import (
+	"errors"
+	"strings"
+)
+
+// Multi is a collection of resources that satisfies the api.Resource interface.
+type Multi []Resource
+
+func (m Multi) String() string {
+	strs := make([]string, 0, len(m))
+
+	for _, res := range m {
+		strs = append(strs, res.String())
+	}
+
+	return strings.Join(strs, ", ")
+}
+
+func (m Multi) ID() string {
+	ids := make([]string, 0, len(m))
+
+	for _, res := range m {
+		ids = append(ids, res.String())
+	}
+
+	return strings.Join(ids, "+")
+}
+
+func (m Multi) Apply() error {
+	var errs []error
+
+	for _, res := range m {
+		errs = append(errs, res.Apply())
+	}
+
+	return errors.Join(errs...)
+}
diff --git a/internal/resource/multi_test.go b/internal/resource/multi_test.go
new file mode 100644
index 0000000..3443afb
--- /dev/null
+++ b/internal/resource/multi_test.go
@@ -0,0 +1,81 @@
+package resource
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestMultiString(t *testing.T) {
+	m := Multi{
+		Resource{Type: "File", Name: "/tmp/a"},
+		Resource{Type: "File", Name: "/tmp/b"},
+	}
+
+	want := "File[/tmp/a], File[/tmp/b]"
+	if got := m.String(); got != want {
+		t.Errorf("Multi.String() = %q, want %q", got, want)
+	}
+}
+
+func TestMultiID(t *testing.T) {
+	m := Multi{
+		Resource{Type: "File", Name: "/tmp/a"},
+		Resource{Type: "File", Name: "/tmp/b"},
+	}
+
+	want := "File[/tmp/a]+File[/tmp/b]"
+	if got := m.ID(); got != want {
+		t.Errorf("Multi.ID() = %q, want %q", got, want)
+	}
+}
+
+func TestMultiApply(t *testing.T) {
+	tests := []struct {
+		name     string
+		appliers []Applier
+		wantErr  bool
+	}{
+		{
+			name: "all success",
+			appliers: []Applier{
+				ApplierFunc(func() error { return nil }),
+				ApplierFunc(func() error { return nil }),
+			},
+			wantErr: false,
+		},
+		{
+			name: "one failure",
+			appliers: []Applier{
+				ApplierFunc(func() error { return nil }),
+				ApplierFunc(func() error { return errors.New("fail 1") }),
+			},
+			wantErr: true,
+		},
+		{
+			name: "multiple failures",
+			appliers: []Applier{
+				ApplierFunc(func() error { return errors.New("fail 1") }),
+				ApplierFunc(func() error { return errors.New("fail 2") }),
+			},
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var resources []Resource
+			for _, app := range tt.appliers {
+				resources = append(resources, Resource{
+					applier: app,
+				})
+			}
+
+			m := Multi(resources)
+			err := m.Apply()
+
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Multi.Apply() error = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}
diff --git a/internal/resource/repository.go b/internal/resource/repository.go
index 215f7e1..0771ef8 100644
--- a/internal/resource/repository.go
+++ b/internal/resource/repository.go
@@ -89,7 +89,7 @@ func (r *repository) apply() error {
 
 	for _, res := range order {
 		log.Printf("Applying resource %v", res)
-		if err := res.Apply.Apply(); err != nil {
+		if err := res.Apply(); err != nil {
 			return fmt.Errorf("failed to apply %v: %w", res, err)
 		}
 	}
diff --git a/internal/resource/repository_test.go b/internal/resource/repository_test.go
index 8f1aef6..f939fca 100644
--- a/internal/resource/repository_test.go
+++ b/internal/resource/repository_test.go
@@ -32,17 +32,17 @@ func TestApply(t *testing.T) {
 				// A depends on B, B depends on C
 				r.registered["A"] = Resource{
 					Type: "T", Name: "A",
-					Apply: &mockApplier{name: "A", logs: logs},
+					applier: &mockApplier{name: "A", logs: logs},
 					dependsOn: map[string]struct{}{"B": {}},
 				}
 				r.registered["B"] = Resource{
 					Type: "T", Name: "B",
-					Apply: &mockApplier{name: "B", logs: logs},
+					applier: &mockApplier{name: "B", logs: logs},
 					dependsOn: map[string]struct{}{"C": {}},
 				}
 				r.registered["C"] = Resource{
 					Type: "T", Name: "C",
-					Apply: &mockApplier{name: "C", logs: logs},
+					applier: &mockApplier{name: "C", logs: logs},
 				}
 			},
 			wantOrder: []string{"C", "B", "A"},
@@ -52,12 +52,12 @@ func TestApply(t *testing.T) {
 			setup: func(r *repository, logs *[]string) {
 				r.registered["A"] = Resource{
 					Type: "T", Name: "A",
-					Apply: &mockApplier{name: "A", logs: logs},
+					applier: &mockApplier{name: "A", logs: logs},
 					dependsOn: map[string]struct{}{"B": {}},
 				}
 				r.registered["B"] = Resource{
 					Type: "T", Name: "B",
-					Apply: &mockApplier{name: "B", logs: logs},
+					applier: &mockApplier{name: "B", logs: logs},
 					dependsOn: map[string]struct{}{"A": {}},
 				}
 			},
@@ -69,7 +69,7 @@ func TestApply(t *testing.T) {
 			setup: func(r *repository, logs *[]string) {
 				r.registered["A"] = Resource{
 					Type: "T", Name: "A",
-					Apply: &mockApplier{name: "A", logs: logs},
+					applier: &mockApplier{name: "A", logs: logs},
 					dependsOn: map[string]struct{}{"Missing": {}},
 				}
 			},
@@ -81,7 +81,7 @@ func TestApply(t *testing.T) {
 			setup: func(r *repository, logs *[]string) {
 				r.registered["A"] = Resource{
 					Type: "T", Name: "A",
-					Apply: &mockApplier{name: "A", err: errors.New("fail A"), logs: logs},
+					applier: &mockApplier{name: "A", err: errors.New("fail A"), logs: logs},
 				}
 			},
 			wantError:   true,
diff --git a/internal/resource/resource.go b/internal/resource/resource.go
index 4e72485..2a01629 100644
--- a/internal/resource/resource.go
+++ b/internal/resource/resource.go
@@ -18,7 +18,7 @@ func (f ApplierFunc) Apply() error {
 type Resource struct {
 	Type      string
 	Name      string
-	Apply     Applier
+	applier   Applier
 	dependsOn map[string]struct{}
 }
 
@@ -26,7 +26,7 @@ func Register(type_, name string, apply Applier) Resource {
 	r := Resource{
 		Type:      type_,
 		Name:      name,
-		Apply:     apply,
+		applier:   apply,
 		dependsOn: make(map[string]struct{}),
 	}
 
@@ -44,3 +44,7 @@ func (r Resource) String() string {
 func (r Resource) ID() string {
 	return fmt.Sprintf("%s[%s]", r.Type, r.Name)
 }
+
+func (r Resource) Apply() error {
+	return r.applier.Apply()
+}