diff --git a/test/assets/integration/a.txt b/test/assets/integration/a.txt
new file mode 100644
index 00000000..8d0585ac
--- /dev/null
+++ b/test/assets/integration/a.txt
@@ -0,0 +1,5 @@
+DO NOT MODIFY ME!
+
+this is "a.txt", a sample input for sigstore-python's unit tests.
+
+DO NOT MODIFY ME!
diff --git a/test/assets/integration/attest/slsa_predicate_v0_2.json b/test/assets/integration/attest/slsa_predicate_v0_2.json
new file mode 100644
index 00000000..95c8fad8
--- /dev/null
+++ b/test/assets/integration/attest/slsa_predicate_v0_2.json
@@ -0,0 +1,249 @@
+{
+    "builder": {
+        "id": "https://github.com/slsa-framework/slsa-github-generator/.github/workflows/generator_generic_slsa3.yml@refs/tags/v2.0.0"
+    },
+    "buildType": "https://github.com/slsa-framework/slsa-github-generator/generic@v1",
+    "invocation": {
+        "configSource": {
+            "uri": "git+https://github.com/sigstore/sigstore-python@refs/tags/v3.2.0",
+            "digest": {
+                "sha1": "fc29ec190575ae345cea23f0953b64ca6f2ab8ba"
+            },
+            "entryPoint": ".github/workflows/release.yml"
+        },
+        "parameters": {},
+        "environment": {
+            "github_actor": "woodruffw",
+            "github_actor_id": "3059210",
+            "github_base_ref": "",
+            "github_event_name": "release",
+            "github_event_payload": {
+                "action": "published",
+                "enterprise": {
+                    "avatar_url": "https://avatars.githubusercontent.com/b/102459?v=4",
+                    "created_at": "2023-12-08T05:54:26Z",
+                    "description": "Open Source Security Foundation (OpenSSF)",
+                    "html_url": "https://github.com/enterprises/openssf",
+                    "id": 102459,
+                    "name": "Open Source Security Foundation",
+                    "node_id": "E_kgDOAAGQOw",
+                    "slug": "openssf",
+                    "updated_at": "2024-01-06T00:47:02Z",
+                    "website_url": "https://openssf.org/"
+                },
+                "organization": {
+                    "avatar_url": "https://avatars.githubusercontent.com/u/71096353?v=4",
+                    "description": "Software Supply Chain Security",
+                    "events_url": "https://api.github.com/orgs/sigstore/events",
+                    "hooks_url": "https://api.github.com/orgs/sigstore/hooks",
+                    "id": 71096353,
+                    "issues_url": "https://api.github.com/orgs/sigstore/issues",
+                    "login": "sigstore",
+                    "members_url": "https://api.github.com/orgs/sigstore/members{/member}",
+                    "node_id": "MDEyOk9yZ2FuaXphdGlvbjcxMDk2MzUz",
+                    "public_members_url": "https://api.github.com/orgs/sigstore/public_members{/member}",
+                    "repos_url": "https://api.github.com/orgs/sigstore/repos",
+                    "url": "https://api.github.com/orgs/sigstore"
+                },
+                "release": {
+                    "assets": [],
+                    "assets_url": "https://api.github.com/repos/sigstore/sigstore-python/releases/170913493/assets",
+                    "author": {
+                        "avatar_url": "https://avatars.githubusercontent.com/u/3059210?v=4",
+                        "events_url": "https://api.github.com/users/woodruffw/events{/privacy}",
+                        "followers_url": "https://api.github.com/users/woodruffw/followers",
+                        "following_url": "https://api.github.com/users/woodruffw/following{/other_user}",
+                        "gists_url": "https://api.github.com/users/woodruffw/gists{/gist_id}",
+                        "gravatar_id": "",
+                        "html_url": "https://github.com/woodruffw",
+                        "id": 3059210,
+                        "login": "woodruffw",
+                        "node_id": "MDQ6VXNlcjMwNTkyMTA=",
+                        "organizations_url": "https://api.github.com/users/woodruffw/orgs",
+                        "received_events_url": "https://api.github.com/users/woodruffw/received_events",
+                        "repos_url": "https://api.github.com/users/woodruffw/repos",
+                        "site_admin": false,
+                        "starred_url": "https://api.github.com/users/woodruffw/starred{/owner}{/repo}",
+                        "subscriptions_url": "https://api.github.com/users/woodruffw/subscriptions",
+                        "type": "User",
+                        "url": "https://api.github.com/users/woodruffw"
+                    },
+                    "body": "### Added\n\n* API: `models.Bundle.BundleType` is now a public API\n  ([#1089](https://github.com/sigstore/sigstore-python/pull/1089))\n\n* CLI: The `sigstore plumbing` subcommand hierarchy has been added. This\n  hierarchy is for *developer-only* interactions, such as fixing malformed\n  Sigstore bundles. These subcommands are **not considered stable until\n  explicitly documented as such**.\n  ([#1089](https://github.com/sigstore/sigstore-python/pull/1089))\n\n### Changed\n\n* CLI: The default console logger now emits to `stderr`, rather than `stdout`\n  ([#1089](https://github.com/sigstore/sigstore-python/pull/1089))\n\n",
+                    "created_at": "2024-08-19T17:14:19Z",
+                    "draft": false,
+                    "html_url": "https://github.com/sigstore/sigstore-python/releases/tag/v3.2.0",
+                    "id": 170913493,
+                    "name": "v3.2.0",
+                    "node_id": "RE_kwDOGq85Ts4KL-7V",
+                    "prerelease": false,
+                    "published_at": "2024-08-19T17:15:11Z",
+                    "tag_name": "v3.2.0",
+                    "tarball_url": "https://api.github.com/repos/sigstore/sigstore-python/tarball/v3.2.0",
+                    "target_commitish": "main",
+                    "upload_url": "https://uploads.github.com/repos/sigstore/sigstore-python/releases/170913493/assets{?name,label}",
+                    "url": "https://api.github.com/repos/sigstore/sigstore-python/releases/170913493",
+                    "zipball_url": "https://api.github.com/repos/sigstore/sigstore-python/zipball/v3.2.0"
+                },
+                "repository": {
+                    "allow_forking": true,
+                    "archive_url": "https://api.github.com/repos/sigstore/sigstore-python/{archive_format}{/ref}",
+                    "archived": false,
+                    "assignees_url": "https://api.github.com/repos/sigstore/sigstore-python/assignees{/user}",
+                    "blobs_url": "https://api.github.com/repos/sigstore/sigstore-python/git/blobs{/sha}",
+                    "branches_url": "https://api.github.com/repos/sigstore/sigstore-python/branches{/branch}",
+                    "clone_url": "https://github.com/sigstore/sigstore-python.git",
+                    "collaborators_url": "https://api.github.com/repos/sigstore/sigstore-python/collaborators{/collaborator}",
+                    "comments_url": "https://api.github.com/repos/sigstore/sigstore-python/comments{/number}",
+                    "commits_url": "https://api.github.com/repos/sigstore/sigstore-python/commits{/sha}",
+                    "compare_url": "https://api.github.com/repos/sigstore/sigstore-python/compare/{base}...{head}",
+                    "contents_url": "https://api.github.com/repos/sigstore/sigstore-python/contents/{+path}",
+                    "contributors_url": "https://api.github.com/repos/sigstore/sigstore-python/contributors",
+                    "created_at": "2022-01-13T17:29:37Z",
+                    "custom_properties": {},
+                    "default_branch": "main",
+                    "deployments_url": "https://api.github.com/repos/sigstore/sigstore-python/deployments",
+                    "description": "A Sigstore client written in Python",
+                    "disabled": false,
+                    "downloads_url": "https://api.github.com/repos/sigstore/sigstore-python/downloads",
+                    "events_url": "https://api.github.com/repos/sigstore/sigstore-python/events",
+                    "fork": false,
+                    "forks": 41,
+                    "forks_count": 41,
+                    "forks_url": "https://api.github.com/repos/sigstore/sigstore-python/forks",
+                    "full_name": "sigstore/sigstore-python",
+                    "git_commits_url": "https://api.github.com/repos/sigstore/sigstore-python/git/commits{/sha}",
+                    "git_refs_url": "https://api.github.com/repos/sigstore/sigstore-python/git/refs{/sha}",
+                    "git_tags_url": "https://api.github.com/repos/sigstore/sigstore-python/git/tags{/sha}",
+                    "git_url": "git://github.com/sigstore/sigstore-python.git",
+                    "has_discussions": false,
+                    "has_downloads": true,
+                    "has_issues": true,
+                    "has_pages": true,
+                    "has_projects": true,
+                    "has_wiki": false,
+                    "homepage": "https://pypi.org/p/sigstore",
+                    "hooks_url": "https://api.github.com/repos/sigstore/sigstore-python/hooks",
+                    "html_url": "https://github.com/sigstore/sigstore-python",
+                    "id": 447691086,
+                    "is_template": false,
+                    "issue_comment_url": "https://api.github.com/repos/sigstore/sigstore-python/issues/comments{/number}",
+                    "issue_events_url": "https://api.github.com/repos/sigstore/sigstore-python/issues/events{/number}",
+                    "issues_url": "https://api.github.com/repos/sigstore/sigstore-python/issues{/number}",
+                    "keys_url": "https://api.github.com/repos/sigstore/sigstore-python/keys{/key_id}",
+                    "labels_url": "https://api.github.com/repos/sigstore/sigstore-python/labels{/name}",
+                    "language": "Python",
+                    "languages_url": "https://api.github.com/repos/sigstore/sigstore-python/languages",
+                    "license": {
+                        "key": "other",
+                        "name": "Other",
+                        "node_id": "MDc6TGljZW5zZTA=",
+                        "spdx_id": "NOASSERTION",
+                        "url": null
+                    },
+                    "merges_url": "https://api.github.com/repos/sigstore/sigstore-python/merges",
+                    "milestones_url": "https://api.github.com/repos/sigstore/sigstore-python/milestones{/number}",
+                    "mirror_url": null,
+                    "name": "sigstore-python",
+                    "node_id": "R_kgDOGq85Tg",
+                    "notifications_url": "https://api.github.com/repos/sigstore/sigstore-python/notifications{?since,all,participating}",
+                    "open_issues": 28,
+                    "open_issues_count": 28,
+                    "owner": {
+                        "avatar_url": "https://avatars.githubusercontent.com/u/71096353?v=4",
+                        "events_url": "https://api.github.com/users/sigstore/events{/privacy}",
+                        "followers_url": "https://api.github.com/users/sigstore/followers",
+                        "following_url": "https://api.github.com/users/sigstore/following{/other_user}",
+                        "gists_url": "https://api.github.com/users/sigstore/gists{/gist_id}",
+                        "gravatar_id": "",
+                        "html_url": "https://github.com/sigstore",
+                        "id": 71096353,
+                        "login": "sigstore",
+                        "node_id": "MDEyOk9yZ2FuaXphdGlvbjcxMDk2MzUz",
+                        "organizations_url": "https://api.github.com/users/sigstore/orgs",
+                        "received_events_url": "https://api.github.com/users/sigstore/received_events",
+                        "repos_url": "https://api.github.com/users/sigstore/repos",
+                        "site_admin": false,
+                        "starred_url": "https://api.github.com/users/sigstore/starred{/owner}{/repo}",
+                        "subscriptions_url": "https://api.github.com/users/sigstore/subscriptions",
+                        "type": "Organization",
+                        "url": "https://api.github.com/users/sigstore"
+                    },
+                    "private": false,
+                    "pulls_url": "https://api.github.com/repos/sigstore/sigstore-python/pulls{/number}",
+                    "pushed_at": "2024-08-19T17:14:57Z",
+                    "releases_url": "https://api.github.com/repos/sigstore/sigstore-python/releases{/id}",
+                    "size": 1835,
+                    "ssh_url": "git@github.com:sigstore/sigstore-python.git",
+                    "stargazers_count": 219,
+                    "stargazers_url": "https://api.github.com/repos/sigstore/sigstore-python/stargazers",
+                    "statuses_url": "https://api.github.com/repos/sigstore/sigstore-python/statuses/{sha}",
+                    "subscribers_url": "https://api.github.com/repos/sigstore/sigstore-python/subscribers",
+                    "subscription_url": "https://api.github.com/repos/sigstore/sigstore-python/subscription",
+                    "svn_url": "https://github.com/sigstore/sigstore-python",
+                    "tags_url": "https://api.github.com/repos/sigstore/sigstore-python/tags",
+                    "teams_url": "https://api.github.com/repos/sigstore/sigstore-python/teams",
+                    "topics": [
+                        "codesigning",
+                        "python",
+                        "security",
+                        "supply-chain"
+                    ],
+                    "trees_url": "https://api.github.com/repos/sigstore/sigstore-python/git/trees{/sha}",
+                    "updated_at": "2024-08-19T17:14:23Z",
+                    "url": "https://api.github.com/repos/sigstore/sigstore-python",
+                    "visibility": "public",
+                    "watchers": 219,
+                    "watchers_count": 219,
+                    "web_commit_signoff_required": true
+                },
+                "sender": {
+                    "avatar_url": "https://avatars.githubusercontent.com/u/3059210?v=4",
+                    "events_url": "https://api.github.com/users/woodruffw/events{/privacy}",
+                    "followers_url": "https://api.github.com/users/woodruffw/followers",
+                    "following_url": "https://api.github.com/users/woodruffw/following{/other_user}",
+                    "gists_url": "https://api.github.com/users/woodruffw/gists{/gist_id}",
+                    "gravatar_id": "",
+                    "html_url": "https://github.com/woodruffw",
+                    "id": 3059210,
+                    "login": "woodruffw",
+                    "node_id": "MDQ6VXNlcjMwNTkyMTA=",
+                    "organizations_url": "https://api.github.com/users/woodruffw/orgs",
+                    "received_events_url": "https://api.github.com/users/woodruffw/received_events",
+                    "repos_url": "https://api.github.com/users/woodruffw/repos",
+                    "site_admin": false,
+                    "starred_url": "https://api.github.com/users/woodruffw/starred{/owner}{/repo}",
+                    "subscriptions_url": "https://api.github.com/users/woodruffw/subscriptions",
+                    "type": "User",
+                    "url": "https://api.github.com/users/woodruffw"
+                }
+            },
+            "github_head_ref": "",
+            "github_ref": "refs/tags/v3.2.0",
+            "github_ref_type": "tag",
+            "github_repository_id": "447691086",
+            "github_repository_owner": "sigstore",
+            "github_repository_owner_id": "71096353",
+            "github_run_attempt": "1",
+            "github_run_id": "10457864437",
+            "github_run_number": "61",
+            "github_sha1": "fc29ec190575ae345cea23f0953b64ca6f2ab8ba"
+        }
+    },
+    "metadata": {
+        "buildInvocationId": "10457864437-1",
+        "completeness": {
+            "parameters": true,
+            "environment": false,
+            "materials": false
+        },
+        "reproducible": false
+    },
+    "materials": [
+        {
+            "uri": "git+https://github.com/sigstore/sigstore-python@refs/tags/v3.2.0",
+            "digest": {
+                "sha1": "fc29ec190575ae345cea23f0953b64ca6f2ab8ba"
+            }
+        }
+    ]
+}
\ No newline at end of file
diff --git a/test/assets/integration/attest/slsa_predicate_v1_0.json b/test/assets/integration/attest/slsa_predicate_v1_0.json
new file mode 100644
index 00000000..fc59b8fc
--- /dev/null
+++ b/test/assets/integration/attest/slsa_predicate_v1_0.json
@@ -0,0 +1,36 @@
+{
+    "buildDefinition": {
+        "buildType": "https://actions.github.io/buildtypes/workflow/v1",
+        "externalParameters": {
+            "workflow": {
+                "ref": "refs/tags/1.21.0",
+                "repository": "https://github.com/octo-org/octo-repo",
+                "path": ".github/workflows/ci.yaml"
+            }
+        },
+        "internalParameters": {
+            "github": {
+                "event_name": "push",
+                "repository_id": "000000000",
+                "repository_owner_id": "0000000",
+                "runner_environment": "github-hosted"
+            }
+        },
+        "resolvedDependencies": [
+            {
+                "uri": "git+https://github.com/octo-org/octo-repo@refs/tags/1.21.0",
+                "digest": {
+                    "gitCommit": "1ac93ce21ee526b36fd154b9058d97dfaa424c50"
+                }
+            }
+        ]
+    },
+    "runDetails": {
+        "builder": {
+            "id": "https://github.com/octo-org/octo-repo/.github/workflows/docker.yaml@refs/heads/development"
+        },
+        "metadata": {
+            "invocationId": "https://github.com/octo-org/octo-repo/actions/runs/10313983218/attempts/2"
+        }
+    }
+}
\ No newline at end of file
diff --git a/test/integration/cli/conftest.py b/test/integration/cli/conftest.py
index 1e689d09..28279535 100644
--- a/test/integration/cli/conftest.py
+++ b/test/integration/cli/conftest.py
@@ -12,17 +12,89 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os
 from pathlib import Path
 from typing import Callable
 
 import pytest
+from id import (
+    AmbientCredentialError,
+    GitHubOidcPermissionCredentialError,
+    detect_credential,
+)
 
 from sigstore._cli import main
+from sigstore.oidc import _DEFAULT_AUDIENCE
 
 _ASSETS = (Path(__file__).parent.parent.parent / "assets/integration").resolve()
 assert _ASSETS.is_dir()
 
 
+def _has_oidc_id():
+    # If there are tokens manually defined for us in the environment, use them.
+    if os.getenv("SIGSTORE_IDENTITY_TOKEN_production") or os.getenv(
+        "SIGSTORE_IDENTITY_TOKEN_staging"
+    ):
+        return True
+
+    try:
+        token = detect_credential(_DEFAULT_AUDIENCE)
+        if token is None:
+            return False
+    except GitHubOidcPermissionCredentialError:
+        # On GitHub Actions, forks do not have access to OIDC identities.
+        # We differentiate this case from other GitHub credential errors,
+        # since it's a case where we want to skip (i.e. return False).
+        if os.getenv("GITHUB_EVENT_NAME") == "pull_request":
+            return False
+        return True
+    except AmbientCredentialError:
+        # If ambient credential detection raises, then we *are* in an ambient
+        # environment but one that's been configured incorrectly. We
+        # pass this through, so that the CI fails appropriately rather than
+        # silently skipping the faulty tests.
+        return True
+
+    return True
+
+
+def pytest_runtest_setup(item):
+    # Do we need a network connection?
+    online = False
+    for mark in ["online", "staging", "production"]:
+        if mark in item.keywords:
+            online = True
+
+    if online and item.config.getoption("--skip-online"):
+        pytest.skip(
+            "skipping test that requires network connectivity due to `--skip-online` flag"
+        )
+    elif "ambient_oidc" in item.keywords and not _has_oidc_id():
+        pytest.skip("skipping test that requires an ambient OIDC credential")
+
+    if "staging" in item.keywords and item.config.getoption("--skip-staging"):
+        pytest.skip(
+            "skipping test that requires staging infrastructure due to `--skip-staging` flag"
+        )
+
+
+def pytest_configure(config):
+    config.addinivalue_line(
+        "markers", "staging: mark test as requiring Sigstore staging infrastructure"
+    )
+    config.addinivalue_line(
+        "markers",
+        "production: mark test as requiring Sigstore production infrastructure",
+    )
+    config.addinivalue_line(
+        "markers",
+        "online: mark test as requiring network connectivity (but not a specific Sigstore infrastructure)",
+    )
+    config.addinivalue_line(
+        "markers", "ambient_oidc: mark test as requiring an ambient OIDC identity"
+    )
+
+
 @pytest.fixture
 def asset():
     def _asset(name: str) -> Path:
diff --git a/test/integration/cli/test_attest.py b/test/integration/cli/test_attest.py
new file mode 100644
index 00000000..510b1a6c
--- /dev/null
+++ b/test/integration/cli/test_attest.py
@@ -0,0 +1,246 @@
+# Copyright 2024 The Sigstore Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from pathlib import Path
+from typing import List, Optional
+
+import pytest
+
+from sigstore.dsse._predicate import PredicateType
+from sigstore.models import Bundle
+from sigstore.verify import Verifier
+from sigstore.verify.policy import UnsafeNoOp
+
+
+def get_cli_params(
+    pred_type: str,
+    pred_path: Path,
+    artifact_path: Path,
+    overwrite: bool = False,
+    bundle_path: Optional[Path] = None,
+) -> List[str]:
+    cli_params = [
+        "--staging",
+        "attest",
+        "--predicate-type",
+        pred_type,
+        "--predicate",
+        str(pred_path),
+    ]
+    if bundle_path is not None:
+        cli_params.extend(["--bundle", str(bundle_path)])
+    if overwrite:
+        cli_params.append("--overwrite")
+    cli_params.append(str(artifact_path))
+
+    return cli_params
+
+
+@pytest.mark.staging
+@pytest.mark.ambient_oidc
+@pytest.mark.parametrize(
+    ("predicate_type", "predicate_filename"),
+    [
+        (PredicateType.SLSA_v0_2, "slsa_predicate_v0_2.json"),
+        (PredicateType.SLSA_v1_0, "slsa_predicate_v1_0.json"),
+    ],
+)
+def test_attest_success_default_output_bundle(
+    capsys, sigstore, asset, predicate_type, predicate_filename
+):
+    predicate_path = asset(f"attest/{predicate_filename}")
+    artifact = asset("a.txt")
+    expected_output_bundle = artifact.with_name("a.txt.sigstore.json")
+
+    assert not expected_output_bundle.exists()
+    sigstore(
+        *get_cli_params(
+            pred_type=predicate_type,
+            pred_path=predicate_path,
+            artifact_path=artifact,
+        )
+    )
+
+    assert expected_output_bundle.exists()
+    verifier = Verifier.staging()
+    with open(expected_output_bundle, "r") as bundle_file, open(
+        artifact, "rb"
+    ) as input_file:
+        bundle = Bundle.from_json(bundle_file.read())
+        input_contents = input_file.read()
+    verifier.verify_artifact(input_=input_contents, bundle=bundle, policy=UnsafeNoOp())
+
+    expected_output_bundle.unlink()
+
+    captures = capsys.readouterr()
+    assert captures.out.endswith(
+        f"Sigstore bundle written to {str(expected_output_bundle)}\n"
+    )
+
+
+@pytest.mark.staging
+@pytest.mark.ambient_oidc
+def test_attest_success_custom_output_bundle(capsys, sigstore, asset, tmp_path):
+    predicate_type = PredicateType.SLSA_v0_2
+    predicate_filename = "slsa_predicate_v0_2.json"
+    predicate_path = asset(f"attest/{predicate_filename}")
+    artifact = asset("a.txt")
+
+    output_bundle = tmp_path / "bundle.json"
+    assert not output_bundle.exists()
+    sigstore(
+        *get_cli_params(
+            pred_type=predicate_type,
+            pred_path=predicate_path,
+            artifact_path=artifact,
+            bundle_path=output_bundle,
+        )
+    )
+
+    assert output_bundle.exists()
+    captures = capsys.readouterr()
+    assert captures.out.endswith(f"Sigstore bundle written to {str(output_bundle)}\n")
+
+
+@pytest.mark.staging
+@pytest.mark.ambient_oidc
+def test_attest_overwrite_existing_bundle(capsys, sigstore, asset, tmp_path):
+    predicate_type = PredicateType.SLSA_v0_2
+    predicate_filename = "slsa_predicate_v0_2.json"
+    predicate_path = asset(f"attest/{predicate_filename}")
+    artifact = asset("a.txt")
+
+    output_bundle = tmp_path / "bundle.json"
+    assert not output_bundle.exists()
+
+    cli_params = get_cli_params(
+        pred_type=predicate_type,
+        pred_path=predicate_path,
+        artifact_path=artifact,
+        bundle_path=output_bundle,
+    )
+    sigstore(*cli_params)
+    assert output_bundle.exists()
+
+    # On invalid argument errors we call `Argumentparser.error`, which prints
+    # a message and exits with code 2
+    with pytest.raises(SystemExit) as e:
+        sigstore(*cli_params)
+    assert e.value.code == 2
+
+    assert output_bundle.exists()
+    captures = capsys.readouterr()
+    assert captures.err.endswith(
+        f"Refusing to overwrite outputs without --overwrite: {str(output_bundle)}\n"
+    )
+
+    cli_params.append("--overwrite")
+    sigstore(*cli_params)
+    assert output_bundle.exists()
+
+    assert captures.out.endswith(f"Sigstore bundle written to {str(output_bundle)}\n")
+
+
+def test_attest_invalid_predicate_type(capsys, sigstore, asset, tmp_path):
+    predicate_type = "invalid_type"
+    predicate_filename = "slsa_predicate_v0_2.json"
+    predicate_path = asset(f"attest/{predicate_filename}")
+    artifact = asset("a.txt")
+
+    output_bundle = tmp_path / "bundle.json"
+    # On invalid argument errors we call `Argumentparser.error`, which prints
+    # a message and exits with code 2
+    with pytest.raises(SystemExit) as e:
+        sigstore(
+            *get_cli_params(
+                pred_type=predicate_type,
+                pred_path=predicate_path,
+                artifact_path=artifact,
+                bundle_path=output_bundle,
+            )
+        )
+    assert e.value.code == 2
+
+    captures = capsys.readouterr()
+    assert captures.err.endswith(f"invalid PredicateType value: '{predicate_type}'\n")
+
+
+def test_attest_mismatching_predicate(capsys, sigstore, asset, tmp_path):
+    predicate_type = PredicateType.SLSA_v0_2
+    predicate_filename = "slsa_predicate_v1_0.json"
+    predicate_path = asset(f"attest/{predicate_filename}")
+    artifact = asset("a.txt")
+
+    output_bundle = tmp_path / "bundle.json"
+    # On invalid argument errors we call `Argumentparser.error`, which prints
+    # a message and exits with code 2
+    with pytest.raises(SystemExit) as e:
+        sigstore(
+            *get_cli_params(
+                pred_type=predicate_type,
+                pred_path=predicate_path,
+                artifact_path=artifact,
+                bundle_path=output_bundle,
+            )
+        )
+    assert e.value.code == 2
+
+    captures = capsys.readouterr()
+    assert f'Unable to parse predicate of type "{predicate_type}":' in captures.err
+
+
+def test_attest_missing_predicate(capsys, sigstore, asset, tmp_path):
+    predicate_type = PredicateType.SLSA_v0_2
+    predicate_filename = "doesnt_exist.json"
+    predicate_path = asset(f"attest/{predicate_filename}")
+    artifact = asset("a.txt")
+
+    output_bundle = tmp_path / "bundle.json"
+    # On invalid argument errors we call `Argumentparser.error`, which prints
+    # a message and exits with code 2
+    with pytest.raises(SystemExit) as e:
+        sigstore(
+            *get_cli_params(
+                pred_type=predicate_type,
+                pred_path=predicate_path,
+                artifact_path=artifact,
+                bundle_path=output_bundle,
+            )
+        )
+    assert e.value.code == 2
+
+    captures = capsys.readouterr()
+    assert captures.err.endswith(f"Predicate must be a file: {predicate_path}\n")
+
+
+def test_attest_invalid_json_predicate(capsys, sigstore, asset, tmp_path):
+    predicate_type = PredicateType.SLSA_v0_2
+    predicate_path = asset("a.txt")
+    artifact = asset("a.txt")
+
+    output_bundle = tmp_path / "bundle.json"
+    # On invalid argument errors we call `Argumentparser.error`, which prints
+    # a message and exits with code 2
+    with pytest.raises(SystemExit) as e:
+        sigstore(
+            *get_cli_params(
+                pred_type=predicate_type,
+                pred_path=predicate_path,
+                artifact_path=artifact,
+                bundle_path=output_bundle,
+            )
+        )
+    assert e.value.code == 2
+
+    captures = capsys.readouterr()
+    assert f'Unable to parse predicate of type "{predicate_type}":' in captures.err