From 81f0d41b5196f0e2e016e7fd6f366aab0a8e657d Mon Sep 17 00:00:00 2001
From: Saurabh Prakash <saurabhp@lambdatest.com>
Date: Thu, 3 Mar 2022 15:22:14 +0530
Subject: [PATCH] Bug fix. Empty base-commit fix

---
 pkg/core/interfaces.go                    |  2 +-
 pkg/core/lifecycle.go                     | 13 +++++++++----
 pkg/diffmanager/setup.go                  |  4 ----
 pkg/testdiscoveryservice/testdiscovery.go |  5 +++--
 4 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/pkg/core/interfaces.go b/pkg/core/interfaces.go
index 51ca06d..9d12c4e 100644
--- a/pkg/core/interfaces.go
+++ b/pkg/core/interfaces.go
@@ -33,7 +33,7 @@ type DiffManager interface {
 // TestDiscoveryService services discovery of tests
 type TestDiscoveryService interface {
 	// Discover executes the test discovery scripts.
-	Discover(ctx context.Context, tasConfig *TASConfig, payload *Payload, secretData map[string]string, diff map[string]int) error
+	Discover(ctx context.Context, tasConfig *TASConfig, payload *Payload, secretData map[string]string, diff map[string]int, diffExists bool) error
 }
 
 // TestBlockListService is used for fetching blocklisted tests
diff --git a/pkg/core/lifecycle.go b/pkg/core/lifecycle.go
index 2ac3a4a..05fc3aa 100644
--- a/pkg/core/lifecycle.go
+++ b/pkg/core/lifecycle.go
@@ -247,15 +247,20 @@ func (pl *Pipeline) Start(ctx context.Context) (err error) {
 		}
 
 		pl.Logger.Infof("Identifying changed files ...")
+		diffExists := true
 		diff, err := pl.DiffManager.GetChangedFiles(ctx, payload, oauth.Data.AccessToken)
 		if err != nil {
-			pl.Logger.Errorf("Unable to identify changed files %s", err)
-			errRemark = "Error occurred in fetching diff from GitHub"
-			return err
+			if errors.Is(err, errs.ErrGitDiffNotFound) {
+				diffExists = false
+			} else {
+				pl.Logger.Errorf("Unable to identify changed files %s", err)
+				errRemark = "Error occurred in fetching diff from GitHub"
+				return err
+			}
 		}
 
 		// discover test cases
-		err = pl.TestDiscoveryService.Discover(ctx, tasConfig, pl.Payload, secretMap, diff)
+		err = pl.TestDiscoveryService.Discover(ctx, tasConfig, pl.Payload, secretMap, diff, diffExists)
 		if err != nil {
 			pl.Logger.Errorf("Unable to perform test discovery: %+v", err)
 			errRemark = "Error occurred in discovering tests"
diff --git a/pkg/diffmanager/setup.go b/pkg/diffmanager/setup.go
index 0dcfb23..2f8c6b0 100644
--- a/pkg/diffmanager/setup.go
+++ b/pkg/diffmanager/setup.go
@@ -212,10 +212,6 @@ func (dm *diffManager) GetChangedFiles(ctx context.Context, payload *core.Payloa
 	} else {
 		diff, err = dm.getCommitDiff(payload.GitProvider, payload.RepoLink, cloneToken, payload.BaseCommit, payload.TargetCommit)
 		if err != nil {
-			if errors.Is(err, errs.ErrGitDiffNotFound) {
-				dm.logger.Debugf("failed to get commit diff for gitprovider: %s error: %v", payload.GitProvider, err)
-				return nil, nil
-			}
 			dm.logger.Errorf("failed to get commit diff for gitprovider: %s error: %v", payload.GitProvider, err)
 			return nil, err
 		}
diff --git a/pkg/testdiscoveryservice/testdiscovery.go b/pkg/testdiscoveryservice/testdiscovery.go
index 1298416..c0443f3 100644
--- a/pkg/testdiscoveryservice/testdiscovery.go
+++ b/pkg/testdiscoveryservice/testdiscovery.go
@@ -27,7 +27,8 @@ func (tds *testDiscoveryService) Discover(ctx context.Context,
 	tasConfig *core.TASConfig,
 	payload *core.Payload,
 	secretData map[string]string,
-	diff map[string]int) error {
+	diff map[string]int,
+	diffExists bool) error {
 	var target []string
 	var envMap map[string]string
 	if payload.EventType == core.EventPullRequest {
@@ -51,7 +52,7 @@ func (tds *testDiscoveryService) Discover(ctx context.Context,
 
 	args := []string{"--command", "discover"}
 	if !discoverAll {
-		if len(diff) == 0 {
+		if len(diff) == 0 && diffExists {
 			// empty diff; in PR, a commit added and then reverted to cause an overall empty PR diff
 			args = append(args, "--diff")
 		} else {