Add -pr for inspecting GitHub pull requests (#11)

* Checkpoint.

* Reorganize main package. Add -pr and -token. Update main package doc comment. Wire up doPR.

* Adjust whitespace in comment template.

* Upgrade go-git dependency.

* Improve (?) isModverComment.

* Oops.

* Take a stab at adding "modver -pr" to the GitHub Actions workflow.

* Wrong version of actions/checkout.

* Disable TestGit for now.

* Some decoupling courtesy of github.com/bobg/decouple.

* Add a test with mocks.

* More test coverage.

* Unskip TestGit.

* Fix (?) broken test.

* If it ain't broke?

* ???

* Grr

* revert revert revert

* Flail flail flail

* Update go-git.

* Skip go-git in GitHub Actions.

* Oops.

* Oh come on.

* Downgrade go-git.

* go mod tidy

* Formatting.

* Add a fetch-master step.

* checkout v3, no -v for go test

* Add a workaround.

* Add a different workaround.

* More test coverage.

* Oops, pass os.Args[1:] to fs.Parse.

* More test coverage.

* More test coverage.

* More test coverage.

.github/workflows/go.yml

@@ -10,22 +10,24 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
-      with:
-        fetch-depth: 0
+      - name: Checkout
+        uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
 
-    - name: Set up Go
-      uses: actions/setup-go@v2
-      with:
-        go-version: 1.18
+      - name: Set up Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: 1.18
 
-    - name: Unit tests
-      run: go test -v -coverprofile=cover.out ./...
+      - name: Unit tests
+        run: go test -coverprofile=cover.out ./...
 
-    - name: Send coverage
-      uses: shogo82148/actions-goveralls@v1
-      with:
-        path-to-profile: cover.out
+      - name: Modver
+        if: ${{ github.event_name == 'pull_request' }}
+        run: go run ./cmd/modver -pr https://github.com/${{ github.repository }}/pull/${{ github.event.number }} -token ${{ github.token }} -pretty
 
-    - name: Version string check
-      run: go run ./cmd/modver -git `pwd`/.git -versions HEAD~1 HEAD
+      - name: Send coverage
+        uses: shogo82148/actions-goveralls@v1
+        with:
+          path-to-profile: cover.out

.gitignore

@@ -1,3 +1,3 @@
 *~
-cover.out
-modver
+/cover.out
+/modver

cmd/modver/comment.md.tmpl

@@ -0,0 +1,35 @@
+# Modver result
+
+This report was generated by [Modver](https://pkg.go.dev/github.com/bobg/modver/v2),
+a Go package and command that helps you obey [semantic versioning rules](https://semver.org/) in your Go module.
+
+{{ if eq .Code "Major" }}
+
+This PR requires an increase in your module’s major version number.
+If the new major version number is 2 or greater,
+you must also add or update the version suffix
+on the module path defined in your `go.mod` file.
+See [the Go Modules Reference](https://go.dev/ref/mod#major-version-suffixes) for more info.
+
+{{ else if eq .Code "Minor" }}
+
+This PR requires (at least) an increase in your module's minor version number.
+
+{{ else if eq .Code "Patchlevel" }}
+
+This PR requires (at least) an increase in your module's patchlevel.
+
+{{ else }}
+
+This PR does not require a change in your module’s version number.
+(You might still consider bumping the patchlevel anyway.)
+
+{{ end }}
+
+{{ if ne .Code "None" }}
+
+```
+{{ .Report -}}
+```
+
+{{ end }}

cmd/modver/compare.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"github.com/google/go-github/v50/github"
+	"github.com/pkg/errors"
+
+	"github.com/bobg/modver/v2"
+)
+
+func doCompare(ctx context.Context, opts options) (modver.Result, error) {
+	if opts.pr != "" {
+		owner, reponame, prnum, err := parsePR(opts.pr)
+		if err != nil {
+			return modver.None, errors.Wrap(err, "parsing pull-request URL")
+		}
+		if opts.ghtoken == "" {
+			return modver.None, fmt.Errorf("usage: %s -pr URL -token TOKEN [-q | -pretty]", os.Args[0])
+		}
+		gh := github.NewTokenClient(ctx, opts.ghtoken)
+		return doPR(ctx, gh, owner, reponame, prnum)
+	}
+
+	if opts.gitRepo != "" {
+		if len(opts.args) != 2 {
+			return nil, fmt.Errorf("usage: %s -git REPO [-gitcmd GIT_COMMAND] [-q | -pretty] [-v1 OLDERVERSION -v2 NEWERVERSION | -versions] OLDERREV NEWERREV", os.Args[0])
+		}
+
+		callback := modver.CompareDirs
+		if opts.versions {
+			callback = getTags(&opts.v1, &opts.v2, opts.args[0], opts.args[1])
+		}
+
+		return modver.CompareGitWith(ctx, opts.gitRepo, opts.args[0], opts.args[1], callback)
+	}
+	if len(opts.args) != 2 {
+		return nil, fmt.Errorf("usage: %s [-q | -pretty] [-v1 OLDERVERSION -v2 NEWERVERSION] OLDERDIR NEWERDIR", os.Args[0])
+	}
+	return modver.CompareDirs(opts.args[0], opts.args[1])
+}

cmd/modver/main.go

@@ -0,0 +1,140 @@
+// Command modver compares two versions of the same Go packages
+// and tells whether a Major, Minor, or Patchlevel version bump
+// (or None)
+// is needed to go from one to the other.
+//
+// Usage:
+//
+//	modver -git REPO [-gitcmd GIT_COMMAND] [-q | -pretty] [-v1 OLDERVERSION -v2 NEWERVERSION | -versions] OLDERREV NEWERREV
+//	modver [-q | -pretty] [-v1 OLDERVERSION -v2 NEWERVERSION] OLDERDIR NEWERDIR
+//	modver -pr URL [-q | -pretty]
+//
+// With `-git REPO`,
+// where REPO is the path to a Git repository,
+// OLDER and NEWER are two revisions in the repository
+// (e.g. hexadecimal SHA strings or "HEAD", etc)
+// containing the older and newer versions of a Go module.
+// Without the -git flag,
+// OLDER and NEWER are two directories containing the older and newer versions of a Go module.
+//
+// With `-gitcmd GIT_COMMAND`,
+// modver uses the given command for Git operations.
+// This is "git" by default.
+// If the command does not exist or is not found in your PATH,
+// modver falls back to using the go-git library.
+//
+// With -v1 and -v2,
+// modver checks whether the change from OLDERVERSION to NEWERVERSION
+// (two version strings)
+// is adequate for the differences detected between OLDER and NEWER.
+// Output is either "OK" or "ERR"
+// (followed by a description)
+// and the exit code is 0 for OK and 1 for ERR.
+// In quiet mode (-q),
+// there is no output.
+// With -git REPO and -versions instead of -v1 and -v2,
+// the values for -v1 and -v2 are determined by querying the repo at the given revisions.
+//
+// Without -v1 and -v2
+// (or -versions),
+// output is a string describing the minimum version-number change required.
+// In quiet mode (-q),
+// there is no output,
+// and the exit status is 0, 1, 2, 3, or 4
+// for None, Patchlevel, Minor, Major, and error.
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os"
+
+	"golang.org/x/mod/semver"
+
+	"github.com/bobg/modver/v2"
+)
+
+const errorStatus = 4
+
+func main() {
+	opts, err := parseArgs()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error parsing args: %s\n", err)
+		os.Exit(errorStatus)
+	}
+
+	ctx := context.Background()
+	if opts.gitCmd != "" {
+		ctx = modver.WithGit(ctx, opts.gitCmd)
+	}
+
+	res, err := doCompare(ctx, opts)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error in comparing: %s\n", err)
+		os.Exit(errorStatus)
+	}
+
+	exitCode := doShowResult(os.Stdout, res, opts)
+	os.Exit(exitCode)
+}
+
+func doShowResult(out io.Writer, res modver.Result, opts options) int {
+	if opts.v1 != "" && opts.v2 != "" {
+		var ok bool
+
+		cmp := semver.Compare(opts.v1, opts.v2)
+		switch res.Code() {
+		case modver.None:
+			ok = cmp <= 0 // v1 <= v2
+
+		case modver.Patchlevel:
+			ok = cmp < 0 // v1 < v2
+
+		case modver.Minor:
+			var (
+				min1 = semver.MajorMinor(opts.v1)
+				min2 = semver.MajorMinor(opts.v2)
+			)
+			ok = semver.Compare(min1, min2) < 0 // min1 < min2
+
+		case modver.Major:
+			var (
+				maj1 = semver.Major(opts.v1)
+				maj2 = semver.Major(opts.v2)
+			)
+			ok = semver.Compare(maj1, maj2) < 0 // maj1 < maj2
+		}
+
+		if ok {
+			if !opts.quiet {
+				if opts.versions {
+					fmt.Fprintf(out, "OK using versions %s and %s: %s\n", opts.v1, opts.v2, res)
+				} else {
+					fmt.Fprintf(out, "OK %s\n", res)
+				}
+			}
+			return 0
+		}
+		if !opts.quiet {
+			if opts.versions {
+				fmt.Fprintf(out, "ERR using versions %s and %s: %s\n", opts.v1, opts.v2, res)
+			} else {
+				fmt.Fprintf(out, "ERR %s\n", res)
+			}
+		}
+		return 1
+	}
+
+	if opts.quiet {
+		return int(res.Code())
+	}
+
+	if opts.pretty {
+		modver.Pretty(out, res)
+	} else {
+		fmt.Fprintln(out, res)
+	}
+
+	return 0
+}

cmd/modver/main_test.go

@@ -0,0 +1,74 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+
+	"github.com/bobg/modver/v2"
+)
+
+func TestDoShowResult(t *testing.T) {
+	cases := []struct {
+		res          modver.Result
+		opts         options
+		wantExitCode int
+		want         string
+	}{{
+		res:          modver.Patchlevel,
+		opts:         options{quiet: true},
+		wantExitCode: int(modver.Patchlevel),
+	}, {
+		res:  modver.Patchlevel,
+		want: modver.Patchlevel.String() + "\n",
+	}, {
+		res:  modver.None,
+		opts: options{v1: "v1.0.0", v2: "v1.0.1"},
+		want: "OK None\n",
+	}, {
+		res:          modver.None,
+		opts:         options{v1: "v1.0.1", v2: "v1.0.0"},
+		want:         "ERR None\n",
+		wantExitCode: 1,
+	}, {
+		res:  modver.Patchlevel,
+		opts: options{v1: "v1.0.0", v2: "v1.0.1"},
+		want: "OK Patchlevel\n",
+	}, {
+		res:          modver.Patchlevel,
+		opts:         options{v1: "v1.0.0", v2: "v1.0.0"},
+		want:         "ERR Patchlevel\n",
+		wantExitCode: 1,
+	}, {
+		res:  modver.Minor,
+		opts: options{v1: "v1.0.0", v2: "v1.1.0"},
+		want: "OK Minor\n",
+	}, {
+		res:          modver.Minor,
+		opts:         options{v1: "v1.0.0", v2: "v1.0.1"},
+		want:         "ERR Minor\n",
+		wantExitCode: 1,
+	}, {
+		res:  modver.Major,
+		opts: options{v1: "v1.0.0", v2: "v2.0.0"},
+		want: "OK Major\n",
+	}, {
+		res:          modver.Major,
+		opts:         options{v1: "v1.0.0", v2: "v1.1.0"},
+		want:         "ERR Major\n",
+		wantExitCode: 1,
+	}}
+
+	for i, tc := range cases {
+		t.Run(fmt.Sprintf("case_%02d", i+1), func(t *testing.T) {
+			buf := new(bytes.Buffer)
+			exitCode := doShowResult(buf, tc.res, tc.opts)
+			if exitCode != tc.wantExitCode {
+				t.Errorf("got exit code %d, want %d", exitCode, tc.wantExitCode)
+			}
+			if buf.String() != tc.want {
+				t.Errorf("got %s, want %s", buf, tc.want)
+			}
+		})
+	}
+}