add assurance tests for auth scheme select (#2730)

.changelog/e9a1faf382294ca19baa08d59a715f4d.json

@@ -0,0 +1,8 @@
+{
+    "id": "e9a1faf3-8229-4ca1-9baa-08d59a715f4d",
+    "type": "bugfix",
+    "description": "Add assurance tests for auth scheme selection logic.",
+    "modules": [
+        "service/s3"
+    ]
+}

service/s3/auth_scheme_test.go

@@ -0,0 +1,163 @@
+package s3
+
+import (
+	"context"
+	"testing"
+
+	smithy "github.com/aws/smithy-go"
+	"github.com/aws/smithy-go/auth"
+	smithyauth "github.com/aws/smithy-go/auth"
+	smithyhttp "github.com/aws/smithy-go/transport/http"
+)
+
+// FUTURE: move to smithy-go, see https://github.com/aws/smithy-go/issues/528
+
+type mockAuthScheme struct {
+	id         string
+	configured bool
+}
+
+var _ smithyhttp.AuthScheme = (*mockAuthScheme)(nil)
+
+func (m *mockAuthScheme) SchemeID() string { return m.id }
+
+func (m *mockAuthScheme) IdentityResolver(_ auth.IdentityResolverOptions) auth.IdentityResolver {
+	if m.configured {
+		return &mockIdentityResolver{}
+	}
+	return nil
+}
+
+func (*mockAuthScheme) Signer() smithyhttp.Signer { return nil }
+
+type mockIdentityResolver struct{}
+
+var _ smithyauth.IdentityResolver = (*mockIdentityResolver)(nil)
+
+func (*mockIdentityResolver) GetIdentity(ctx context.Context, props smithy.Properties) (smithyauth.Identity, error) {
+	return nil, nil
+}
+
+func contains(have []string, want string) bool {
+	for _, v := range have {
+		if v == want {
+			return true
+		}
+	}
+	return false
+}
+
+func TestSelectScheme(t *testing.T) {
+	for name, c := range map[string]struct {
+		Supported  []string
+		Configured []string
+		Expect     string
+	}{
+		"support(sigv4, bearer) + cfg(sigv4, bearer) = sigv4": {
+			Supported: []string{
+				smithyauth.SchemeIDSigV4,
+				smithyauth.SchemeIDHTTPBearer,
+			},
+			Configured: []string{
+				smithyauth.SchemeIDSigV4,
+				smithyauth.SchemeIDHTTPBearer,
+			},
+			Expect: smithyauth.SchemeIDSigV4,
+		},
+		"support(sigv4, bearer) + cfg(bearer) = bearer": {
+			Supported: []string{
+				smithyauth.SchemeIDSigV4,
+				smithyauth.SchemeIDHTTPBearer,
+			},
+			Configured: []string{
+				smithyauth.SchemeIDHTTPBearer,
+			},
+			Expect: smithyauth.SchemeIDHTTPBearer,
+		},
+		"support(sigv4, bearer) + cfg(sigv4) = sigv4": {
+			Supported: []string{
+				smithyauth.SchemeIDSigV4,
+				smithyauth.SchemeIDHTTPBearer,
+			},
+			Configured: []string{
+				smithyauth.SchemeIDSigV4,
+			},
+			Expect: smithyauth.SchemeIDSigV4,
+		},
+		"support(sigv4, bearer) + cfg(n/a) = error": {
+			Supported: []string{
+				smithyauth.SchemeIDSigV4,
+				smithyauth.SchemeIDHTTPBearer,
+			},
+			Configured: []string{},
+			Expect:     "",
+		},
+		"support(sigv4) + cfg(bearer) = error": {
+			Supported: []string{
+				smithyauth.SchemeIDSigV4,
+			},
+			Configured: []string{
+				smithyauth.SchemeIDHTTPBearer,
+			},
+			Expect: "",
+		},
+		"support(anon) + cfg(sigv4) = anon": {
+			Supported: []string{
+				smithyauth.SchemeIDAnonymous,
+			},
+			Configured: []string{
+				smithyauth.SchemeIDSigV4,
+			},
+			Expect: smithyauth.SchemeIDAnonymous,
+		},
+		"support(anon) + cfg(n/a) = anon": {
+			Supported: []string{
+				smithyauth.SchemeIDAnonymous,
+			},
+			Configured: []string{},
+			Expect:     smithyauth.SchemeIDAnonymous,
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			authopts := []*smithyauth.Option{}
+			for _, id := range c.Supported {
+				authopts = append(authopts, &smithyauth.Option{
+					SchemeID: id,
+				})
+			}
+
+			m := &resolveAuthSchemeMiddleware{
+				options: Options{
+					AuthSchemes: []smithyhttp.AuthScheme{
+						&mockAuthScheme{
+							id:         smithyauth.SchemeIDSigV4,
+							configured: contains(c.Configured, smithyauth.SchemeIDSigV4),
+						},
+						&mockAuthScheme{
+							id:         smithyauth.SchemeIDHTTPBearer,
+							configured: contains(c.Configured, smithyauth.SchemeIDHTTPBearer),
+						},
+						&mockAuthScheme{
+							id:         smithyauth.SchemeIDAnonymous,
+							configured: true,
+						},
+					},
+				},
+			}
+
+			scheme, ok := m.selectScheme(authopts)
+			if c.Expect != "" {
+				if !ok {
+					t.Errorf("expected scheme '%s', got none", c.Expect)
+				}
+				if actual := scheme.Scheme.SchemeID(); c.Expect != actual {
+					t.Errorf("expected scheme '%s', got '%s'", c.Expect, actual)
+				}
+			} else {
+				if ok {
+					t.Errorf("expected no scheme, got '%s'", scheme.Scheme.SchemeID())
+				}
+			}
+		})
+	}
+}