terraform: Add more tests for cases we felt weren't well covered

terraform/context_test.go

@@ -2861,6 +2861,35 @@ func TestContextPlan(t *testing.T) {
 	}
 }
 
+func TestContextPlan_emptyDiff(t *testing.T) {
+	m := testModule(t, "plan-empty")
+	p := testProvider("aws")
+	p.DiffFn = func(
+		info *InstanceInfo,
+		s *InstanceState,
+		c *ResourceConfig) (*InstanceDiff, error) {
+		return nil, nil
+	}
+
+	ctx := testContext(t, &ContextOpts{
+		Module: m,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+	})
+
+	plan, err := ctx.Plan(nil)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(plan.String())
+	expected := strings.TrimSpace(testTerraformPlanEmptyStr)
+	if actual != expected {
+		t.Fatalf("bad:\n%s", actual)
+	}
+}
+
 func TestContextPlan_minimal(t *testing.T) {
 	m := testModule(t, "plan-empty")
 	p := testProvider("aws")

terraform/graph_test.go

@@ -786,6 +786,77 @@ func TestGraphAddDiff_module_depends(t *testing.T) {
 	}
 }
 
+func TestGraphAddDiff_moduleDependsModule(t *testing.T) {
+	m := testModule(t, "graph-diff-module-dep-module")
+	diff := &Diff{
+		Modules: []*ModuleDiff{
+			&ModuleDiff{
+				Path:    []string{"root"},
+				Destroy: true,
+			},
+			&ModuleDiff{
+				Path:    []string{"root", "foo"},
+				Destroy: true,
+				Resources: map[string]*InstanceDiff{
+					"aws_instance.foo": &InstanceDiff{
+						Destroy: true,
+					},
+				},
+			},
+			&ModuleDiff{
+				Path:    []string{"root", "bar"},
+				Destroy: true,
+				Resources: map[string]*InstanceDiff{
+					"aws_instance.foo": &InstanceDiff{
+						Destroy: true,
+					},
+				},
+			},
+		},
+	}
+	state := &State{
+		Modules: []*ModuleState{
+			&ModuleState{
+				Path: []string{"root", "foo"},
+				Resources: map[string]*ResourceState{
+					"aws_instance.foo": &ResourceState{
+						Type: "aws_instance",
+						Primary: &InstanceState{
+							ID: "foo",
+						},
+					},
+				},
+			},
+
+			&ModuleState{
+				Path: []string{"root", "bar"},
+				Resources: map[string]*ResourceState{
+					"aws_instance.foo": &ResourceState{
+						Type: "aws_instance",
+						Primary: &InstanceState{
+							ID: "foo",
+						},
+					},
+				},
+				Dependencies: []string{
+					"module.foo",
+				},
+			},
+		},
+	}
+
+	g, err := Graph(&GraphOpts{Module: m, Diff: diff, State: state})
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(g.String())
+	expected := strings.TrimSpace(testTerraformGraphDiffModuleDependsModuleStr)
+	if actual != expected {
+		t.Fatalf("bad:\n\n%s", actual)
+	}
+}
+
 func TestGraphAddDiff_createBeforeDestroy(t *testing.T) {
 	m := testModule(t, "graph-diff-create-before")
 	diff := &Diff{
@@ -1345,6 +1416,16 @@ root
   root -> module.orphan
 `
 
+const testTerraformGraphDiffModuleDependsModuleStr = `
+root: root
+module.bar
+module.foo
+  module.foo -> module.bar
+root
+  root -> module.bar
+  root -> module.foo
+`
+
 const testTerraformGraphModulesStr = `
 root: root
 aws_instance.web

terraform/test-fixtures/graph-diff-module-dep-module/bar/main.tf

@@ -0,0 +1,3 @@
+variable "in" {}
+
+aws_instance "foo" {}

terraform/test-fixtures/graph-diff-module-dep-module/foo/main.tf

@@ -0,0 +1,5 @@
+output "data" {
+    value = "foo"
+}
+
+aws_instance "foo" {}

terraform/test-fixtures/graph-diff-module-dep-module/main.tf

@@ -0,0 +1,8 @@
+module "foo" {
+    source = "./foo"
+}
+
+module "bar" {
+    source = "./bar"
+    in = "${module.foo.data}"
+}