Generalise interleaving of test data

test/git-lfs-test-server-api/main.go

@@ -243,6 +243,32 @@ func callBatchApi(op string, objs []TestObject) ([]*lfs.ObjectResource, error) {
 	return lfs.Batch(apiobjs, op)
 }
 
+// Combine 2 slices into one by "randomly" interleaving
+// Not actually random, same sequence each time so repeatable
+func interleaveTestData(slice1, slice2 []TestObject) []TestObject {
+	// Predictable sequence, mixin existing & missing semi-randomly
+	rand.Seed(21)
+	count := len(slice1) + len(slice2)
+	ret := make([]TestObject, 0, count)
+	slice1Idx := 0
+	slice2Idx := 0
+	for left := count; left > 0; {
+		for i := rand.Intn(3) + 1; slice1Idx < len(slice1) && i > 0; i-- {
+			obj := slice1[slice1Idx]
+			ret = append(ret, obj)
+			slice1Idx++
+			left--
+		}
+		for i := rand.Intn(3) + 1; slice2Idx < len(slice2) && i > 0; i-- {
+			obj := slice2[slice2Idx]
+			ret = append(ret, obj)
+			slice2Idx++
+			left--
+		}
+	}
+	return ret
+}
+
 func init() {
 	RootCmd.Flags().StringVarP(&apiUrl, "url", "u", "", "URL of the API (must supply this or --clone)")
 	RootCmd.Flags().StringVarP(&cloneUrl, "clone", "c", "", "Clone URL from which to find API (must supply this or --url)")

test/git-lfs-test-server-api/testdownload.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"math/rand"
 
 	"github.com/github/git-lfs/lfs"
 )
@@ -72,37 +71,22 @@ func downloadAllMissing(oidsExist, oidsMissing []TestObject) error {
 func downloadMixed(oidsExist, oidsMissing []TestObject) error {
 
 	existSet := lfs.NewStringSetWithCapacity(len(oidsExist))
+	for _, o := range oidsExist {
+		existSet.Add(o.Oid)
+	}
 	missingSet := lfs.NewStringSetWithCapacity(len(oidsMissing))
-
-	// Predictable sequence, mixin existing & missing semi-randomly
-	rand.Seed(21)
-	count := len(oidsExist) + len(oidsMissing)
-	calloids := make([]TestObject, 0, count)
-	existIdx := 0
-	missingIdx := 0
-	for left := count; left > 0; {
-		for i := rand.Intn(3) + 1; existIdx < len(oidsExist) && i > 0; i-- {
-			obj := oidsExist[existIdx]
-			existSet.Add(obj.Oid)
-			calloids = append(calloids, obj)
-			existIdx++
-			left--
-		}
-		for i := rand.Intn(3) + 1; missingIdx < len(oidsMissing) && i > 0; i-- {
-			obj := oidsMissing[missingIdx]
-			missingSet.Add(obj.Oid)
-			calloids = append(calloids, obj)
-			missingIdx++
-			left--
-		}
+	for _, o := range oidsMissing {
+		missingSet.Add(o.Oid)
 	}
 
+	calloids := interleaveTestData(oidsExist, oidsMissing)
 	retobjs, err := callBatchApi("download", calloids)
 
 	if err != nil {
 		return err
 	}
 
+	count := len(oidsExist) + len(oidsMissing)
 	if len(retobjs) != count {
 		return fmt.Errorf("Incorrect number of returned objects, expected %d, got %d", count, len(retobjs))
 	}