Override provider schemas for mocked providers (#34481)

* Override provider schemas for mocked providers

* address comments

internal/providers/mock.go

@@ -41,6 +41,23 @@ func (m *Mock) GetProviderSchema() GetProviderSchemaResponse {
 	if m.schema == nil {
 		// Cache the schema, it's not changing.
 		schema := m.Provider.GetProviderSchema()
+
+		// Override the provider schema with the constant mock provider schema.
+		// This is empty at the moment, check configs/mock_provider.go for the
+		// actual schema.
+		//
+		// The GetProviderSchemaResponse is returned by value, so it should be
+		// safe for us to modify directly, without affecting any shared state
+		// that could be in use elsewhere.
+		schema.Provider = Schema{
+			Version: schema.Provider.Version,
+			Block:   nil, // Empty - we support no blocks or attributes in mock provider configurations.
+		}
+
+		// Note, we leave the resource and data source schemas as they are since
+		// we want to be able to validate those configurations against the real
+		// provider schemas.
+
 		m.schema = &schema
 	}
 	return *m.schema

internal/terraform/context_apply2_test.go

@@ -2492,6 +2492,151 @@ resource "test_object" "foo" {
 	}
 }
 
+func TestContext2Apply_mockProviderRequiredSchema(t *testing.T) {
+	m := testModuleInline(t, map[string]string{
+		"main.tf": `
+provider "test" {}
+
+data "test_object" "foo" {}
+
+resource "test_object" "foo" {
+	value = data.test_object.foo.output
+}
+`,
+	})
+
+	// Manually mark the provider config as being mocked.
+	m.Module.ProviderConfigs["test"].Mock = true
+	m.Module.ProviderConfigs["test"].MockData = &configs.MockData{
+		MockDataSources: map[string]*configs.MockResource{
+			"test_object": {
+				Mode: addrs.DataResourceMode,
+				Type: "test_object",
+				Defaults: cty.ObjectVal(map[string]cty.Value{
+					"output": cty.StringVal("expected data output"),
+				}),
+			},
+		},
+		MockResources: map[string]*configs.MockResource{
+			"test_object": {
+				Mode: addrs.ManagedResourceMode,
+				Type: "test_object",
+				Defaults: cty.ObjectVal(map[string]cty.Value{
+					"output": cty.StringVal("expected resource output"),
+				}),
+			},
+		},
+	}
+
+	// This time our test provider has a required attribute that we don't
+	// provide in the configuration. The fact we've marked this provider as a
+	// mock means the missing required attribute doesn't matter.
+
+	testProvider := &MockProvider{
+		GetProviderSchemaResponse: &providers.GetProviderSchemaResponse{
+			Provider: providers.Schema{
+				Block: &configschema.Block{
+					Attributes: map[string]*configschema.Attribute{
+						"required": {
+							Type:     cty.String,
+							Required: true,
+						},
+					},
+				},
+			},
+			ResourceTypes: map[string]providers.Schema{
+				"test_object": {
+					Block: &configschema.Block{
+						Attributes: map[string]*configschema.Attribute{
+							"value": {
+								Type:     cty.String,
+								Required: true,
+							},
+							"output": {
+								Type:     cty.String,
+								Computed: true,
+							},
+						},
+					},
+				},
+			},
+			DataSources: map[string]providers.Schema{
+				"test_object": {
+					Block: &configschema.Block{
+						Attributes: map[string]*configschema.Attribute{
+							"output": {
+								Type:     cty.String,
+								Computed: true,
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	reachedReadDataSourceFn := false
+	reachedPlanResourceChangeFn := false
+	reachedApplyResourceChangeFn := false
+	testProvider.ReadDataSourceFn = func(request providers.ReadDataSourceRequest) (resp providers.ReadDataSourceResponse) {
+		reachedReadDataSourceFn = true
+		cfg := request.Config.AsValueMap()
+		cfg["output"] = cty.StringVal("unexpected data output")
+		resp.State = cty.ObjectVal(cfg)
+		return resp
+	}
+	testProvider.PlanResourceChangeFn = func(request providers.PlanResourceChangeRequest) (resp providers.PlanResourceChangeResponse) {
+		reachedPlanResourceChangeFn = true
+		cfg := request.Config.AsValueMap()
+		cfg["output"] = cty.UnknownVal(cty.String)
+		resp.PlannedState = cty.ObjectVal(cfg)
+		return resp
+	}
+	testProvider.ApplyResourceChangeFn = func(request providers.ApplyResourceChangeRequest) (resp providers.ApplyResourceChangeResponse) {
+		reachedApplyResourceChangeFn = true
+		cfg := request.Config.AsValueMap()
+		cfg["output"] = cty.StringVal("unexpected resource output")
+		resp.NewState = cty.ObjectVal(cfg)
+		return resp
+	}
+
+	ctx := testContext2(t, &ContextOpts{
+		Providers: map[addrs.Provider]providers.Factory{
+			addrs.NewDefaultProvider("test"): testProviderFuncFixed(testProvider),
+		},
+	})
+
+	plan, diags := ctx.Plan(m, states.NewState(), &PlanOpts{
+		Mode: plans.NormalMode,
+	})
+	if diags.HasErrors() {
+		t.Fatalf("expected no errors, but got %s", diags)
+	}
+
+	state, diags := ctx.Apply(plan, m, nil)
+	if diags.HasErrors() {
+		t.Fatalf("expected no errors, but got %s", diags)
+	}
+
+	// Check we never made it to the actual provider.
+	if reachedReadDataSourceFn {
+		t.Errorf("read the data source in the provider when it should have been mocked")
+	}
+	if reachedPlanResourceChangeFn {
+		t.Errorf("planned the resource in the provider when it should have been mocked")
+	}
+	if reachedApplyResourceChangeFn {
+		t.Errorf("applied the resource in the provider when it should have been mocked")
+	}
+
+	// Check we got the right data back from our mocked provider.
+	instance := state.ResourceInstance(mustResourceInstanceAddr("test_object.foo"))
+	expected := "{\"output\":\"expected resource output\",\"value\":\"expected data output\"}"
+	if diff := cmp.Diff(string(instance.Current.AttrsJSON), expected); len(diff) > 0 {
+		t.Errorf("expected:\n%s\nactual:\n%s\ndiff:\n%s", expected, string(instance.Current.AttrsJSON), diff)
+	}
+}
+
 func TestContext2Apply_forget(t *testing.T) {
 	addrA := mustResourceInstanceAddr("test_object.a")
 	m := testModuleInline(t, map[string]string{