improvement: better error when attempting to run outside of git repo

Closes #1194

garden-service/src/vcs/git.ts

@@ -73,13 +73,32 @@ export class GitHandler extends VcsHandler {
     }
   }
 
+  async getRepoRoot(log: LogEntry, path: string) {
+    const git = this.gitCli(log, path)
+
+    try {
+      return (await git("rev-parse", "--show-toplevel"))[0]
+    } catch (err) {
+      if (err.exitCode === 128) {
+        // Throw nice error when we detect that we're not in a repo root
+        throw new RuntimeError(deline`
+          Path ${path} is not in a git repository root. Garden must be run from within a git repo.
+          Please run \`git init\` if you're starting a new project and repository, or move the project to an
+          existing repository, and try again.
+        `, { path })
+      } else {
+        throw err
+      }
+    }
+  }
+
   /**
    * Returns a list of files, along with file hashes, under the given path, taking into account the configured
    * .ignore files, and the specified include/exclude filters.
    */
   async getFiles({ log, path, include, exclude }: GetFilesParams): Promise<VcsFile[]> {
     const git = this.gitCli(log, path)
-    const gitRoot = (await git("rev-parse", "--show-toplevel"))[0]
+    const gitRoot = await this.getRepoRoot(log, path)
 
     // List modified files, so that we can ensure we have the right hash for them later
     const modified = new Set((await this.getModifiedFiles(git, path))

garden-service/src/vcs/vcs.ts

@@ -88,6 +88,7 @@ export abstract class VcsHandler {
   constructor(protected gardenDirPath: string, protected ignoreFiles: string[]) { }
 
   abstract name: string
+  abstract async getRepoRoot(log: LogEntry, path: string): Promise<string>
   abstract async getFiles(params: GetFilesParams): Promise<VcsFile[]>
   abstract async ensureRemoteSource(params: RemoteSourceParams): Promise<string>
   abstract async updateRemoteSource(params: RemoteSourceParams): Promise<void>

garden-service/test/unit/src/vcs/git.ts

@@ -18,6 +18,7 @@ import { getCommitIdFromRefList, parseGitUrl, GitHandler } from "../../../../src
 import { fixedExcludes } from "../../../../src/util/fs"
 import { LogEntry } from "../../../../src/logger/log-entry"
 import { hashRepoUrl } from "../../../../src/util/ext-source-util"
+import { deline } from "../../../../src/util/string"
 
 // Overriding this to make sure any ignorefile name is respected
 const defaultIgnoreFilename = ".testignore"
@@ -56,7 +57,7 @@ async function addToIgnore(tmpPath: string, pathToExclude: string, ignoreFilenam
 describe("GitHandler", () => {
   let tmpDir: tmp.DirectoryResult
   let tmpPath: string
-  let git
+  let git: any
   let handler: GitHandler
   let log: LogEntry
 
@@ -74,6 +75,30 @@ describe("GitHandler", () => {
     await tmpDir.cleanup()
   })
 
+  describe("getRepoRoot", () => {
+    it("should return the repo root if it is the same as the given path", async () => {
+      const path = tmpPath
+      expect(await handler.getRepoRoot(log, path)).to.equal(tmpPath)
+    })
+
+    it("should return the nearest repo root, given a subpath of that repo", async () => {
+      const dirPath = join(tmpPath, "dir")
+      await mkdir(dirPath)
+      expect(await handler.getRepoRoot(log, dirPath)).to.equal(tmpPath)
+    })
+
+    it("should throw a nice error when given a path outside of a repo", async () => {
+      await expectError(
+        () => handler.getRepoRoot(log, "/tmp"),
+        (err) => expect(err.message).to.equal(deline`
+          Path /tmp is not in a git repository root. Garden must be run from within a git repo.
+          Please run \`git init\` if you're starting a new project and repository, or move the project to
+          an existing repository, and try again.
+        `),
+      )
+    })
+  })
+
   describe("getFiles", () => {
     it("should work with no commits in repo", async () => {
       expect(await handler.getFiles({ path: tmpPath, log })).to.eql([])

garden-service/test/unit/src/vcs/vcs.ts

@@ -25,6 +25,10 @@ class TestVcsHandler extends VcsHandler {
   name = "test"
   private testVersions: TreeVersions = {}
 
+  async getRepoRoot() {
+    return "/foo"
+  }
+
   async getFiles() {
     return []
   }