From 22b2bad96835651b133c898f0a301d7e0006a0c7 Mon Sep 17 00:00:00 2001
From: Vladimir Mikryukov <vmikryukov@gmail.com>
Date: Mon, 7 Oct 2024 20:26:07 +0300
Subject: [PATCH] upd `TestMainFunction` - test version, no inp, non-existent
 inp, valid inp

---
 seqhasher_test.go | 95 +++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 84 insertions(+), 11 deletions(-)

diff --git a/seqhasher_test.go b/seqhasher_test.go
index 01bea50..33f58df 100644
--- a/seqhasher_test.go
+++ b/seqhasher_test.go
@@ -433,20 +433,93 @@ func TestAll(t *testing.T) {
 }
 
 func TestMainFunction(t *testing.T) {
-	// Set up arguments
-	oldArgs := os.Args
-	os.Args = []string{"cmd", "-version"}
+	tests := []struct {
+		name           string
+		args           []string
+		expectedOutput string
+		expectedError  bool
+		checkUsage     bool
+	}{
+		{
+			name:           "Version flag",
+			args:           []string{"cmd", "-version"},
+			expectedOutput: fmt.Sprintf("SeqHasher %s\n", version),
+			expectedError:  false,
+		},
+		{
+			name:       "No input file",
+			args:       []string{"cmd"},
+			checkUsage: true,
+		},
+		{
+			name:           "Non-existent input file",
+			args:           []string{"cmd", "nonexistent_file.fasta"},
+			expectedOutput: "Error opening input: open nonexistent_file.fasta: no such file or directory\n",
+			expectedError:  true,
+		},
+		{
+			name:           "Valid input file",
+			args:           []string{"cmd", testFastaPath},
+			expectedOutput: "", // The actual output will be the processed sequences
+			expectedError:  false,
+		},
+	}
 
-	// Call run() instead of main()
-	output := run()
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Reset flags before each test
+			flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
 
-	// Restore arguments
-	os.Args = oldArgs
+			// Set up arguments
+			oldArgs := os.Args
+			os.Args = tt.args
 
-	// Check if version is printed
-	expectedOutput := fmt.Sprintf("SeqHasher %s\n", version)
-	if output != expectedOutput {
-		t.Errorf("Expected output %q, got %q", expectedOutput, output)
+			// Capture stdout and stderr
+			oldStdout := os.Stdout
+			oldStderr := os.Stderr
+			r, w, _ := os.Pipe()
+			os.Stdout = w
+			os.Stderr = w
+
+			// Call run() instead of main()
+			output := run()
+
+			// Restore stdout and stderr
+			w.Close()
+			os.Stdout = oldStdout
+			os.Stderr = oldStderr
+
+			// Read captured output
+			var buf bytes.Buffer
+			io.Copy(&buf, r)
+			capturedOutput := buf.String()
+
+			// Restore arguments
+			os.Args = oldArgs
+
+			// Check output
+			if tt.expectedError {
+				if output != tt.expectedOutput {
+					t.Errorf("Expected error output %q, got %q", tt.expectedOutput, output)
+				}
+			} else if tt.checkUsage {
+				if !strings.Contains(capturedOutput, "Usage:") {
+					t.Errorf("Expected usage information, but it was not printed")
+				}
+			} else {
+				if tt.expectedOutput != "" && output != tt.expectedOutput {
+					t.Errorf("Expected output %q, got %q", tt.expectedOutput, output)
+				}
+				if tt.expectedOutput == "" && output == "" {
+					t.Errorf("Expected non-empty output, got empty string")
+				}
+			}
+
+			// For the "Valid input file" case, check if the output contains processed sequences
+			if tt.name == "Valid input file" && !strings.Contains(output, ";seq1\n") {
+				t.Errorf("Expected processed sequences in output, but they were not found")
+			}
+		})
 	}
 }