fix: throw when detecting a shallow clone

* fix: warn about shallow clones

* docs: help with shallow clone troubleshooting

* closes #7
* closes #12

* test: simplify repo setup and teardown

package.json

@@ -68,7 +68,7 @@
   },
   "repository": {
     "type": "git",
-    "url": "git+https://github.com/marionebl/conventional-changelog-lint.git"
+    "url": "https://github.com/marionebl/conventional-changelog-lint.git"
   },
   "bugs": {
     "url": "https://github.com/marionebl/conventional-changelog-lint/issues"

readme.md

@@ -29,7 +29,7 @@ resolves `extends` configurations.
 
 ```shell
 ❯ conventional-changelog-lint --help
-  conventional-changelog-lint@0.1.0 - Lint commit messages against a conventional-changelog preset and ruleset
+  conventional-changelog-lint - Lint commit messages against a conventional-changelog preset and ruleset
 
   [input] reads from stdin if --edit, --from, --to are omitted
   --color,-c    toggle formatted output, defaults to: true
@@ -42,6 +42,41 @@ resolves `extends` configurations.
 
 ```
 
+### Recipes
+
+#### git hook
+As a `commitmsg` git-hook with ["husky"](https://git.io/JDwyQg)
+
+```json
+  {
+    "scripts": {
+      "commitmsg": "conventional-changelog-lint -e"
+    }
+  }
+```
+
+
+#### Last commit
+As part of `npm test`
+
+```json
+  {
+    "scripts": {
+      "test": "conventional-changelog-lint --from=HEAD~1"
+    }
+  }
+```
+
+#### Travis
+
+```yml
+# Force full git checkout
+before_install: git fetch --unshallow
+
+# Lint all commits not in the target branch
+before_script: conventional-changelog-lint --from=$TRAVIS_BRANCH to=$TRAVIS_PULL_REQUEST_BRANCH
+```
+
 ### API
 
 The programming interface does not read configuration by default,
@@ -77,28 +112,6 @@ const report = lint(
 );
 ```
 
-### Recipes
-
-*   As a `commitmsg` git-hook with ["husky"](https://git.io/JDwyQg)
-
-```json
-  {
-    "scripts": {
-      "commitmsg": "conventional-changelog-lint -e"
-    }
-  }
-```
-
-*   As part of `npm test`
-
-```json
-  {
-    "scripts": {
-      "test": "conventional-changelog-lint --from=HEAD~1"
-    }
-  }
-```
-
 ## Configuration
 
 `conventional-changelog-lint` is configured via
@@ -186,6 +199,45 @@ wildcards: {
 }
 ```
 
+## Shallow clones
+
+### TL;DR
+
+Perform `git fetch --shallow` before linting.
+
+Most likely you are reading this because you where presented with an error message:
+
+```
+  'Could not get git history from shallow clone. 
+  Use git fetch --shallow before linting.
+  Original issue: https://git.io/vyKMq\n Refer to https://git.io/vyKMv for details.'
+```
+
+### Explanation
+
+git supports checking out `shallow` clones of a repository to save bandwith in times.
+These limited copies do not contain a full git history. This makes `conventional-changelog-lint`
+fail, especially when running on large commit ranges. 
+To ensure linting works every time you should convert a shallow git repo to a complete one.
+Use `git fetch --shallow` to do so.
+
+### Travis
+
+Ensure full git checkouts on TravisCI, add to `.travis.yml`:
+
+```yml
+before_install: 
+  - git fetch --unshallow
+```
+
+### Appveyor
+
+Ensure full git checkouts on AppVeyor, add to `appveyor.yml`:
+
+```yml
+shallow_clone: false
+```
+
 ## Supported Node.js versions
 
 conventional-changelog-lint supports the active Node.js [LTS](https://github.com/nodejs/LTS#lts-schedule) version and higher: `>= 4`

source/library/get-messages.js

@@ -1,10 +1,17 @@
 import {join} from 'path';
+import exists from 'path-exists';
 import gitRawCommits from 'git-raw-commits';
 import gitToplevel from 'git-toplevel';
 import {readFile} from 'mz/fs';
 
 export default getCommitMessages;
 
+const SHALLOW_MESSAGE = [
+	'Could not get git history from shallow clone.',
+	'Use git fetch --shallow before linting.',
+	'Original issue: https://git.io/vyKMq\n Refer to https://git.io/vyKMv for details.'
+].join('\n');
+
 // Get commit messages
 // Object => Promise<Array<String>>
 async function getCommitMessages(settings) {
@@ -14,6 +21,10 @@ async function getCommitMessages(settings) {
 		return getEditCommit();
 	}
 
+	if (await isShallow()) {
+		throw new Error(SHALLOW_MESSAGE);
+	}
+
 	return await getHistoryCommits({from, to});
 }
 
@@ -31,6 +42,14 @@ function getHistoryCommits(options) {
 	});
 }
 
+// Check if the current repository is shallow
+// () => Promise<Boolean>
+async function isShallow() {
+	const top = await gitToplevel();
+	const shallow = join(top, '.git/shallow');
+	return await exists(shallow);
+}
+
 // Get recently edited commit message
 // () => Promise<Array<String>>
 async function getEditCommit() {

test/integration/get-messages.js

@@ -11,25 +11,36 @@ import rimraf from 'rimraf';
 import expect from 'unexpected';
 
 import getMessages from '../../source/library/get-messages';
+import pkg from '../../package';
 
 const rm = denodeify(rimraf);
 
-test.serial('get edit commit message from git root', async () => {
-	const repo = await initRepository();
+test.beforeEach(async t => {
+	t.context.repos = [await initRepository()];
+});
+
+test.afterEach.always(async t => {
+	try {
+		await Promise.all(t.context.repos.map(async repo => cleanRepository(repo)));
+		t.context.repos = [];
+	} catch (err) {
+		console.log({err});
+	}
+});
+
+test.serial('get edit commit message from git root', async t => {
+	const [repo] = t.context.repos;
 
 	await writeFile('alpha.txt', 'alpha');
 	await execa('git', ['add', '.']);
 	await execa('git', ['commit', '-m', 'alpha']);
-
 	const expected = ['alpha\n\n'];
 	const actual = await getMessages({edit: true});
 	expect(actual, 'to equal', expected);
-
-	await cleanRepository(repo);
 });
 
-test.serial('get history commit messages', async () => {
-	const repo = await initRepository();
+test.serial('get history commit messages', async t => {
+	const [repo] = t.context.repos;
 
 	await writeFile('alpha.txt', 'alpha');
 	await execa('git', ['add', 'alpha.txt']);
@@ -40,12 +51,10 @@ test.serial('get history commit messages', async () => {
 	const expected = ['remove alpha\n\n', 'alpha\n\n'];
 	const actual = await getMessages({});
 	expect(actual, 'to equal', expected);
-
-	await cleanRepository(repo);
 });
 
-test.serial('get edit commit message from git subdirectory', async () => {
-	const repo = await initRepository();
+test.serial('get edit commit message from git subdirectory', async t => {
+	const [repo] = t.context.repos;
 
 	await mkdir('beta');
 	await writeFile('beta/beta.txt', 'beta');
@@ -56,8 +65,20 @@ test.serial('get edit commit message from git subdirectory', async () => {
 	const expected = ['beta\n\n'];
 	const actual = await getMessages({edit: true});
 	expect(actual, 'to equal', expected);
+});
+
+test.serial('get history commit messages from shallow clone', async t => {
+	const [repo] = t.context.repos;
+
+	await writeFile('alpha.txt', 'alpha');
+	await execa('git', ['add', 'alpha.txt']);
+	await execa('git', ['commit', '-m', 'alpha']);
+
+	const clone = await cloneRepository(pkg.repository.url, repo, '--depth', '1');
+	t.context.repos = [...t.context.repos, clone];
 
-	await cleanRepository(repo);
+	const err = await t.throws(getMessages({from: 'master'}));
+	expect(err.message, 'to contain', 'Could not get git history from shallow clone');
 });
 
 async function initRepository() {
@@ -74,8 +95,21 @@ async function initRepository() {
 	return {directory, previous};
 }
 
+async function cloneRepository(source, context, ...args) {
+	const directory = join(tmpdir(), rand());
+	await execa('git', ['clone', ...args, source, directory]);
+	process.chdir(directory);
+
+	await execa('git', ['config', 'user.email', 'test@example.com']);
+	await execa('git', ['config', 'user.name', 'ava']);
+
+	return {directory, previous: context.previous};
+}
+
 async function cleanRepository(repo) {
-	process.chdir(repo.previous);
+	if (repo.previous && repo.previous !== process.cwd()) {
+		process.chdir(repo.previous);
+	}
 
 	if (await exists(repo.directory)) {
 		await rm(repo.directory);