Introduce changes.patrol files for more flexible tests

Author: rentziass

README.md

@@ -104,5 +104,9 @@ like Patrol. You can take a look at any of the case defined in
   trying to test
 - add as many folders as you'd like to `patrol/testdata/{your-test}/commits`.
   Each folder represents an actual commit, and they will be applied on top of
-  each other as real commits when tests are run.
+  each other as real commits when tests are run. Each commit following the first
+  one should contain a `changes.patrol` file that lists the output you expect
+  from Patrol for that test (don't worry, order doesn't matter here). You can
+  check this
+  [example](patrol/testdata/internalchanges/commits/2/changes.patrol).
 - add a new test case in [patrol/repo\_test.go](patrol/repo_test.go)

patrol/patrol_test.go

@@ -1,6 +1,7 @@
 package patrol_test
 
 import (
+	"bufio"
 	"errors"
 	"fmt"
 	"io/ioutil"
@@ -27,13 +28,6 @@ type RepoTest struct {
 
 	// description of the test, what are trying to assess?
 	Description string
-
-	// the git revision against which changes should be detected
-	TestAgainstRevision string
-
-	// the list of expected packages that should be flagged as changed between
-	// HEAD and TestAgainstRevision
-	ExpectedChangedPackages []string
 }
 
 func (test *RepoTest) Run(t *testing.T) {
@@ -75,19 +69,38 @@ func (test *RepoTest) Run(t *testing.T) {
 		})
 		require.NoError(t, err)
 
+		// avoid running patrol on first commit, there was nothing before
 		if previousCommit != "" {
+			expected := expectedChanges(t, tmp)
+
 			r, err := patrol.NewRepo(tmp)
 			require.NoError(t, err)
 
 			changes, err := r.ChangesFrom(previousCommit)
 			require.NoError(t, err)
-			assert.ElementsMatch(t, test.ExpectedChangedPackages, changes, test.Name+": expected changes do not match")
+			assert.ElementsMatch(t, expected, changes, test.Name+": expected changes do not match")
 		}
 
 		previousCommit = commit.String()
 	}
 }
 
+func expectedChanges(t *testing.T, dir string) []string {
+	file, err := os.Open(filepath.Join(dir, "changes.patrol"))
+	require.NoError(t, err)
+	defer file.Close()
+
+	var changes []string
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		changes = append(changes, scanner.Text())
+	}
+
+	require.NoError(t, scanner.Err())
+
+	return changes
+}
+
 type RepoTests []RepoTest
 
 func (tests RepoTests) Run(t *testing.T) {

patrol/repo_test.go

@@ -9,38 +9,24 @@ func TestRepo(t *testing.T) {
 			Name:           "change within module",
 			Description: "A change to a package within the same module\n" +
 				"should flag depending packages as changed",
-			ExpectedChangedPackages: []string{
-				"github.com/utilitywarehouse/internalchange/internal/bar",
-				"github.com/utilitywarehouse/internalchange/pkg/foo",
-				"github.com/utilitywarehouse/internalchange/pkg/cat",
-			},
 		},
 		RepoTest{
 			TestdataFolder: "modules",
 			Name:           "change in go modules dependency",
 			Description: "A change to a go modules dependency\n" +
 				"should flag depending packages as changed",
-			ExpectedChangedPackages: []string{
-				"github.com/utilitywarehouse/modules",
-			},
 		},
 		RepoTest{
 			TestdataFolder: "vendoring",
 			Name:           "change in vendored dependencies",
 			Description: "A change to a vendored dependency\n" +
 				"should flag depending packages as changed",
-			ExpectedChangedPackages: []string{
-				"github.com/utilitywarehouse/vendoring",
-			},
 		},
 		RepoTest{
 			TestdataFolder: "exportedtesting",
 			Name:           "change in a package with packagename_test test package",
 			Description: "A change to package x that is being tested " +
 				"using x_test package should not result in a stack overflow :D",
-			ExpectedChangedPackages: []string{
-				"github.com/utilitywarehouse/exportedtesting/foo",
-			},
 		},
 	}
 

patrol/testdata/exportedtesting/commits/2/changes.patrol

@@ -0,0 +1 @@
+github.com/utilitywarehouse/exportedtesting/foo

patrol/testdata/internalchange/commits/2/changes.patrol

@@ -0,0 +1,3 @@
+github.com/utilitywarehouse/internalchange/internal/bar
+github.com/utilitywarehouse/internalchange/pkg/foo
+github.com/utilitywarehouse/internalchange/pkg/cat

patrol/testdata/internalchange/commits/3/changes.patrol

@@ -0,0 +1,3 @@
+github.com/utilitywarehouse/internalchange/internal/bar
+github.com/utilitywarehouse/internalchange/pkg/foo
+github.com/utilitywarehouse/internalchange/pkg/cat

patrol/testdata/modules/commits/2/changes.patrol

@@ -0,0 +1 @@
+github.com/utilitywarehouse/modules

patrol/testdata/vendoring/commits/2/changes.patrol

@@ -0,0 +1 @@
+github.com/utilitywarehouse/vendoring