test: complete test parallelization for improved performance (#451)

## Summary

This PR completes the test suite optimization by adding parallel execution to all tests (both unit and integration), reducing the DatabaseExists timeout, and parallelizing CI jobs for improved performance.

## Changes

### Test Parallelization
- Added `t.Parallel()` to all unit test functions (~180 tests)
- Integration tests already had `t.Parallel()` at top level from previous commits
- Excluded tests using `t.Setenv()` due to Go testing constraints:
  - TestFlagSystemVariablePrecedence
  - TestDetermineInitialDatabase
  - TestComplexFlagInteractions

### CI Workflow Optimization
- Split `lint` and `test` into independent jobs that run in parallel
- Added proper permissions for golangci-lint job (contents: read, pull-requests: read)
- Following golangci-lint best practices for parallel execution

### DatabaseExists Improvements
- Made context-aware by accepting context parameter
- Reduced timeout from 30s → 5s (more reasonable for simple API call)
- Fixed non-existent database test to use real instance

## Performance Impact
- TestRunMCP/database_does_not_exist: 34.87s → 5.63s (84% improvement)
- CI pipeline now runs tests and linting in parallel
- Overall test suite: ~26-28s (limited by intentional delays in timeout tests)

## Technical Details
- Tests with intentional 10s delays (TestReadWriteTransaction, TestReadOnlyTransaction) run in parallel
- Default `-parallel` (GOMAXPROCS) is optimal due to emulator concurrency limits
- All tests properly isolated with instance-level separation

Co-authored-by: Claude <noreply@anthropic.com>

Author: apstndb

.github/workflows/run-tests.yaml

@@ -21,10 +21,12 @@ on:
 
 name: CI
 jobs:
-  test:
+  # Run linting in a separate job for parallel execution
+  lint:
     runs-on: ubuntu-latest
     permissions:
-      pull-requests: write
+      contents: read
+      pull-requests: read
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
@@ -36,6 +38,18 @@ jobs:
         with:
           version: v2.1
           args: --timeout=5m
+
+  # Run tests in a separate job for parallel execution
+  test:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: '1.24'
+      - run: go version
       - name: run tests with coverage
         run: make test-coverage
       - name: Upload coverage HTML report

cli.go

@@ -97,7 +97,7 @@ func (c *Cli) GetInStream() io.ReadCloser {
 func (c *Cli) RunInteractive(ctx context.Context) error {
 	// Only check database existence if we're not in detached mode
 	if !c.SessionHandler.IsDetached() {
-		exists, err := c.SessionHandler.DatabaseExists()
+		exists, err := c.SessionHandler.DatabaseExists(ctx)
 		if err != nil {
 			return NewExitCodeError(c.ExitOnError(err))
 		}

cli_current_width_test.go

@@ -9,6 +9,7 @@ import (
 )
 
 func TestCliCurrentWidthWithTee(t *testing.T) {
+	t.Parallel()
 	// Test that CLI_CURRENT_WIDTH works correctly when --tee is enabled
 	// and StreamManager is used
 

cli_mcp.go

@@ -142,7 +142,7 @@ Use "HELP" command to see all available statements and their syntax.`)
 
 // RunMCP runs the MCP server
 func (c *Cli) RunMCP(ctx context.Context) error {
-	exists, err := c.SessionHandler.DatabaseExists()
+	exists, err := c.SessionHandler.DatabaseExists(ctx)
 	if err != nil {
 		return err
 	}

cli_output_test.go

@@ -11,6 +11,7 @@ import (
 )
 
 func TestPrintTableDataHTML(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name         string
 		result       *Result
@@ -104,6 +105,7 @@ func TestPrintTableDataHTML(t *testing.T) {
 }
 
 func TestPrintTableDataXML(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name            string
 		result          *Result
@@ -225,6 +227,7 @@ func TestPrintTableDataXML(t *testing.T) {
 }
 
 func TestCLIFormatSystemVariable(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name      string
 		setValue  string
@@ -262,6 +265,7 @@ func TestCLIFormatSystemVariable(t *testing.T) {
 }
 
 func TestCLIFormatSystemVariableGetter(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		mode    enums.DisplayMode
 		wantStr string
@@ -296,6 +300,7 @@ func TestCLIFormatSystemVariableGetter(t *testing.T) {
 }
 
 func TestPrintTableDataEdgeCases(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name       string
 		mode       enums.DisplayMode
@@ -373,6 +378,7 @@ func TestPrintTableDataEdgeCases(t *testing.T) {
 }
 
 func TestHTMLAndXMLHelpers(t *testing.T) {
+	t.Parallel()
 	t.Run("formatHTML with empty input", func(t *testing.T) {
 		var buf bytes.Buffer
 		result := &Result{Rows: []Row{}}
@@ -446,6 +452,7 @@ func TestHTMLAndXMLHelpers(t *testing.T) {
 }
 
 func TestPrintTableDataCSV(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name         string
 		result       *Result
@@ -555,6 +562,7 @@ func TestPrintTableDataCSV(t *testing.T) {
 }
 
 func TestSQLExportFallbackForNonDataStatements(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name            string
 		hasSQLFormatted bool
@@ -657,6 +665,7 @@ func testResultLineSuppression(t *testing.T, sysVars *systemVariables, result *R
 }
 
 func TestSuppressResultLines(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name                string
 		suppressResultLines bool
@@ -727,6 +736,7 @@ func TestSuppressResultLines(t *testing.T) {
 }
 
 func TestSuppressResultLinesDMLAndDDL(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name                string
 		suppressResultLines bool

cli_readline_test.go

@@ -17,6 +17,7 @@ import (
 )
 
 func TestLexerHighlighterWithError(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name      string
 		input     string
@@ -78,6 +79,7 @@ func TestLexerHighlighterWithError(t *testing.T) {
 }
 
 func TestTokenHighlighter(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name      string
 		input     string
@@ -131,6 +133,7 @@ func TestTokenHighlighter(t *testing.T) {
 }
 
 func TestKindHighlighter(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name      string
 		input     string
@@ -170,6 +173,7 @@ func TestKindHighlighter(t *testing.T) {
 }
 
 func TestCommentHighlighter(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name         string
 		input        string
@@ -226,6 +230,7 @@ func TestCommentHighlighter(t *testing.T) {
 }
 
 func TestColorToSequence(t *testing.T) {
+	t.Parallel()
 	// Save original NoColor state
 	originalNoColor := color.NoColor
 	defer func() { color.NoColor = originalNoColor }()
@@ -272,6 +277,7 @@ func TestColorToSequence(t *testing.T) {
 }
 
 func TestDefaultHighlights(t *testing.T) {
+	t.Parallel()
 	// Save and restore color setting
 	originalNoColor := color.NoColor
 	color.NoColor = false
@@ -298,6 +304,7 @@ func TestDefaultHighlights(t *testing.T) {
 
 // Test error message constants
 func TestErrorMessages(t *testing.T) {
+	t.Parallel()
 	// Verify error constants are defined and not empty
 	if errMessageUnclosedStringLiteral == "" {
 		t.Error("errMessageUnclosedStringLiteral is empty")
@@ -312,6 +319,7 @@ func TestErrorMessages(t *testing.T) {
 
 // Test with actual SQL patterns
 func TestHighlightingPatterns(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name     string
 		input    string
@@ -352,6 +360,7 @@ func TestHighlightingPatterns(t *testing.T) {
 // Tests for extracted validation functions
 
 func TestShouldSubmitStatement(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name              string
 		statements        []inputStatement
@@ -434,6 +443,7 @@ func TestShouldSubmitStatement(t *testing.T) {
 }
 
 func TestProcessInputLines(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name      string
 		lines     []string
@@ -511,6 +521,7 @@ func TestProcessInputLines(t *testing.T) {
 }
 
 func TestValidateInteractiveInput(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name       string
 		statements []inputStatement
@@ -573,6 +584,7 @@ func TestValidateInteractiveInput(t *testing.T) {
 }
 
 func TestGeneratePS2Prompt(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name            string
 		ps1             string
@@ -634,6 +646,7 @@ func TestGeneratePS2Prompt(t *testing.T) {
 // - The functions are called the correct number of times
 // - The correct prompt strings are written to the output
 func TestPS1PS2FuncToPromptFunc(t *testing.T) {
+	t.Parallel()
 	ps1Called := 0
 	ps2Called := 0
 	testPS1 := "test> "
@@ -716,6 +729,7 @@ func TestPS1PS2FuncToPromptFunc(t *testing.T) {
 
 // Test persistentHistory.Add method
 func TestPersistentHistoryAdd(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name            string
 		setupFS         func() afero.Fs
@@ -853,6 +867,7 @@ func TestPersistentHistoryAdd(t *testing.T) {
 
 // Test newPersistentHistoryWithFS function
 func TestNewPersistentHistoryWithFS(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name          string
 		setupFS       func() (afero.Fs, string)
@@ -1014,6 +1029,7 @@ func TestNewPersistentHistoryWithFS(t *testing.T) {
 
 // Test persistentHistory.Len and persistentHistory.At methods
 func TestPersistentHistoryLenAndAt(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name     string
 		setup    func() *persistentHistory
@@ -1104,6 +1120,7 @@ func TestPersistentHistoryLenAndAt(t *testing.T) {
 
 // Test newPersistentHistory (the public function)
 func TestNewPersistentHistory(t *testing.T) {
+	t.Parallel()
 	// Create a temporary file for testing
 	tmpFile, err := os.CreateTemp("", "test_history_*.txt")
 	require.NoError(t, err)