Make TailTest less flaky (#2)

This change accounts for the fact that Tail.Stop() and the events from
inotify have no way of being synchronized, so the test now allows for
all the observable variants.

It also runs the test 100 times just to make sure it's not flaky in the
future.

.github/workflows/ci.yml

@@ -36,13 +36,13 @@ jobs:
         run: golint -set_exit_status ./...
 
       - name: Get dependencies
-        run: go get -tags=static -t -v ./...
+        run: go get -t -v ./...
 
       - name: Vet
-        run: go vet -tags=static -v ./...
+        run: go vet -v ./...
 
       - name: Test
-        run: go test -tags=static -v  -race -coverprofile=coverage.txt -covermode=atomic ./...
+        run: go test -count=100 -v -race -coverprofile=coverage.txt -covermode=atomic ./...
 
       - name: Ensure formatting
         run: |

.github/workflows/release.yml

@@ -22,7 +22,7 @@ jobs:
         id: go
 
       - name: Get dependencies
-        run: go get -tags=static -t -v ./...
+        run: go get -t -v ./...
 
       - name: Bump version and push tag
         id: bump-version
@@ -37,7 +37,6 @@ jobs:
           mkdir -p artifacts/usr/bin/
           go build -o artifacts/usr/bin/omegaup-logslurp \
             -ldflags "-X main.ProgramVersion=${{ steps.bump-version.outputs.tag }}" \
-            -tags=static \
             github.com/omegaup/logslurp/cmd/omegaup-logslurp
 
       - name: Package

tail_test.go

@@ -32,17 +32,11 @@ func TestTail(t *testing.T) {
 	originalInode := tail.Inode()
 
 	doneChan := make(chan struct{})
+	var buf bytes.Buffer
 	go func() {
-		var buf bytes.Buffer
 		if _, err := io.Copy(&buf, tail); err != nil {
 			t.Errorf("Failed to read file: %v", err)
 		}
-		if err := tail.Close(); err != nil {
-			t.Errorf("Failed to close file: %v", err)
-		}
-		if buf.String() != "1\n2\n3\n" {
-			t.Errorf("Failed to read file, got %q, want %q", buf.String(), "1\n2\n3\n")
-		}
 		close(doneChan)
 	}()
 
@@ -68,8 +62,34 @@ func TestTail(t *testing.T) {
 	tail.Stop()
 
 	<-doneChan
+	if err := tail.Close(); err != nil {
+		t.Errorf("Failed to close file: %v", err)
+	}
 	finalInode := tail.Inode()
 
+	// There is a small problem here: tail.Stop() immediately stops reading from
+	// the inotify stream. There is no easy way to synchronize both events
+	// without poking into the implementation details of Tail.
+	//
+	// It is completely valid to have the contents of the stream be "1\n",
+	// "1\n2\n", and "1\n\2\n3\n". In the two versions, there is no guarantee
+	// about what the value of the final inode should be, since those events
+	// could feasibly appear in the stream after calling `tail.Stop()`.
+	if buf.String() == "1\n" {
+		t.Logf("Very short version detected, inode should still be the old one")
+		if finalInode != originalInode {
+			t.Errorf("Failed to detect the new inode, got %v, want %v", finalInode, originalInode)
+		}
+		return
+	}
+	if buf.String() == "1\n2\n" {
+		t.Logf("Short version detected, no guarantee about the inode")
+		return
+	}
+
+	if buf.String() != "1\n2\n3\n" {
+		t.Errorf("Failed to read file, got %q, want %q", buf.String(), "1\n2\n3\n")
+	}
 	if finalInode == originalInode {
 		t.Errorf("Failed to read new inode, got %v, want !%v", finalInode, originalInode)
 	}