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Add state preserving plan modifiers (#204)
Add a UseStateForUnknown plan modifier.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,3 @@ | ||
| ```release-note:feature | ||
| Added `tfsdk.UseStateForUnknown()` as a built-in plan modifier, which will automatically replace an unknown value in the plan with the value from the state. This mimics the behavior of computed and optional+computed values in Terraform Plugin SDK versions 1 and 2. Provider developers will likely want to use it for "write-once" attributes that never change once they're set in state. | ||
| ``` |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,162 @@ | ||
| package tfsdk | ||
|
|
||
| import ( | ||
| "context" | ||
| "testing" | ||
|
|
||
| "github.com/google/go-cmp/cmp" | ||
| "github.com/hashicorp/terraform-plugin-framework/attr" | ||
| "github.com/hashicorp/terraform-plugin-framework/types" | ||
| "github.com/hashicorp/terraform-plugin-go/tftypes" | ||
| ) | ||
|
|
||
| func TestUseStateForUnknownModifier(t *testing.T) { | ||
| t.Parallel() | ||
|
|
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| type testCase struct { | ||
| state attr.Value | ||
| plan attr.Value | ||
| config attr.Value | ||
| expected attr.Value | ||
| } | ||
|
|
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| tests := map[string]testCase{ | ||
| "nil-state": { | ||
| // this honestly just shouldn't happen, but let's be | ||
| // sure we're not going to panic if it does | ||
| state: nil, | ||
| plan: types.String{Unknown: true}, | ||
| config: types.String{Null: true}, | ||
| expected: types.String{Unknown: true}, | ||
| }, | ||
| "nil-plan": { | ||
| // this honestly just shouldn't happen, but let's be | ||
| // sure we're not going to panic if it does | ||
| state: types.String{Null: true}, | ||
| plan: nil, | ||
| config: types.String{Null: true}, | ||
| expected: nil, | ||
| }, | ||
| "null-state": { | ||
| // when we first create the resource, use the unknown | ||
| // value | ||
| state: types.String{Null: true}, | ||
| plan: types.String{Unknown: true}, | ||
| config: types.String{Null: true}, | ||
| expected: types.String{Unknown: true}, | ||
| }, | ||
| "known-plan": { | ||
| // this would really only happen if we had a plan | ||
| // modifier setting the value before this plan modifier | ||
| // got to it | ||
| // | ||
| // but we still want to preserve that value, in this | ||
| // case | ||
| state: types.String{Value: "foo"}, | ||
| plan: types.String{Value: "bar"}, | ||
| config: types.String{Null: true}, | ||
| expected: types.String{Value: "bar"}, | ||
| }, | ||
| "non-null-state-unknown-plan": { | ||
| // this is the situation we want to preserve the state | ||
| // in | ||
| state: types.String{Value: "foo"}, | ||
| plan: types.String{Unknown: true}, | ||
| config: types.String{Null: true}, | ||
| expected: types.String{Value: "foo"}, | ||
| }, | ||
| "unknown-config": { | ||
| // this is the situation in which a user is | ||
| // interpolating into a field. We want that to still | ||
| // show up as unknown, otherwise they'll get apply-time | ||
| // errors for changing the value even though we knew it | ||
| // was legitimately possible for it to change and the | ||
| // provider can't prevent this from happening | ||
| state: types.String{Value: "foo"}, | ||
| plan: types.String{Unknown: true}, | ||
| config: types.String{Unknown: true}, | ||
| expected: types.String{Unknown: true}, | ||
| }, | ||
| } | ||
|
|
||
| for name, tc := range tests { | ||
| name, tc := name, tc | ||
| t.Run(name, func(t *testing.T) { | ||
| t.Parallel() | ||
|
|
||
| schema := Schema{ | ||
| Attributes: map[string]Attribute{ | ||
| "a": { | ||
| Type: types.StringType, | ||
| Optional: true, | ||
| Computed: true, | ||
| }, | ||
| }, | ||
| } | ||
|
|
||
| var configRaw, planRaw, stateRaw interface{} | ||
| if tc.config != nil { | ||
| val, err := tc.config.ToTerraformValue(context.Background()) | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
| configRaw = val | ||
| } | ||
| if tc.state != nil { | ||
| val, err := tc.state.ToTerraformValue(context.Background()) | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
| stateRaw = val | ||
| } | ||
| if tc.plan != nil { | ||
| val, err := tc.plan.ToTerraformValue(context.Background()) | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
| planRaw = val | ||
| } | ||
| configVal := tftypes.NewValue(tftypes.String, configRaw) | ||
| stateVal := tftypes.NewValue(tftypes.String, stateRaw) | ||
| planVal := tftypes.NewValue(tftypes.String, planRaw) | ||
|
|
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| req := ModifyAttributePlanRequest{ | ||
| AttributePath: tftypes.NewAttributePath(), | ||
| Config: Config{ | ||
| Schema: schema, | ||
| Raw: tftypes.NewValue(schema.TerraformType(context.Background()), map[string]tftypes.Value{ | ||
| "a": configVal, | ||
| }), | ||
| }, | ||
| State: State{ | ||
| Schema: schema, | ||
| Raw: tftypes.NewValue(schema.TerraformType(context.Background()), map[string]tftypes.Value{ | ||
| "a": stateVal, | ||
| }), | ||
| }, | ||
| Plan: Plan{ | ||
| Schema: schema, | ||
| Raw: tftypes.NewValue(schema.TerraformType(context.Background()), map[string]tftypes.Value{ | ||
| "a": planVal, | ||
| }), | ||
| }, | ||
| AttributeConfig: tc.config, | ||
| AttributeState: tc.state, | ||
| AttributePlan: tc.plan, | ||
| ProviderMeta: Config{}, | ||
| } | ||
| resp := &ModifyAttributePlanResponse{ | ||
| AttributePlan: req.AttributePlan, | ||
| } | ||
| modifier := UseStateForUnknown() | ||
|
|
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| modifier.Modify(context.Background(), req, resp) | ||
| if resp.Diagnostics.HasError() { | ||
| t.Fatalf("Unexpected diagnostics: %s", resp.Diagnostics) | ||
| } | ||
| if diff := cmp.Diff(tc.expected, resp.AttributePlan); diff != "" { | ||
| t.Errorf("Unexpected diff (-wanted, +got): %s", diff) | ||
| } | ||
| }) | ||
| } | ||
| } |