Bash function to run only tests that changed vs main branch

tdiff.sh

#!/bin/bash

# 🚀 Run Only Changed Tests - Git Diff Integration Test Runner
#
# Stop running entire test suites! This script automatically detects and runs only 
# the integration tests that have changed in your git branch vs master.
#
# ⚡ SPEED UP YOUR WORKFLOW:
# • Runs only modified .test.ts files in __integrations__/ 
# • Extracts specific test names from git diff (it/describe blocks)
# • Smart fallback to full file tests if extraction fails
# • Watch mode for continuous testing
#
# 💡 PERFECT FOR:
# • TDD/BDD development workflows
# • Large test suites that take too long
# • CI/CD optimization 
# • Mocha/Jest integration testing
#
# 📖 USAGE:
#   tdiff-integration              # Run changed tests once
#   WATCH=true tdiff-integration   # Watch mode with nodemon
#
# Keywords: git diff testing, selective test runner, integration tests, 
# mocha grep, jest filter, test automation, ci optimization, tdd workflow

function tdiff-integration {
  TEST_FILES=$(
    git diff --name-only origin/master
    git ls-files --others --exclude-standard
  )

  if [[ -z "$TEST_FILES" ]]; then
    echo "No test files changed against master"
  else
    # Filter only .test.ts files in __integrations__ directory
    INTEGRATION_FILES=$(echo "$TEST_FILES" | grep '__integrations__.*\.test\.ts$')

    if [[ -z "$INTEGRATION_FILES" ]]; then
      echo "No integration .test.ts files changed against master"
    else
      echo "Running specific integration test files:"
      echo "$INTEGRATION_FILES"
      cat .envrc.local
      source .envrc.local

      # Extract changed test names from git diff with improved regex
      echo "🔍 Starting test name extraction..."
      CHANGED_TESTS=""
      
      # Process each file individually by reading line by line
      while IFS= read -r file; do
        if [[ -n "$file" ]]; then
          echo "📁 Processing file: $file"
          # Check if file exists to avoid git diff errors
          if [[ -f "$file" ]]; then
            echo "✅ File exists, getting git diff..."
            # Get added/modified lines that contain 'it(' or 'describe(' with better pattern matching
            DIFF_OUTPUT=$(git diff origin/master -- "$file")
            echo "📝 Git diff output lines: $(echo "$DIFF_OUTPUT" | wc -l)"
            
            ADDED_LINES=$(echo "$DIFF_OUTPUT" | grep '^+')
            echo "➕ Added lines count: $(echo "$ADDED_LINES" | wc -l)"
            
            TEST_LINES=$(echo "$ADDED_LINES" | grep -E '^\+\s*(it|describe)\s*\(')
            echo "🧪 Test lines found: $(echo "$TEST_LINES" | wc -l)"
            if [[ -n "$TEST_LINES" ]]; then
              echo "🧪 Test lines content:"
              echo "$TEST_LINES"
            fi
            
            echo "🔧 Simple test name extraction..."
            echo "Raw test lines:"
            echo "$TEST_LINES"
            
            # Super simple approach: use grep to extract quotes and backticks
            TESTS=""
            while IFS= read -r line; do
              if [[ -n "$line" ]]; then
                echo "🔧 Processing line: '$line'"
                # Extract anything in double quotes
                quoted_text=$(echo "$line" | grep -o '"[^"]*"' | sed 's/"//g')
                if [[ -n "$quoted_text" ]]; then
                  echo "✅ Found quoted text: '$quoted_text'"
                  TESTS="$TESTS$quoted_text"$'\n'
                else
                  # Try backticks - get first word after backtick
                  backtick_text=$(echo "$line" | grep -o '`[^`]*' | sed 's/`//' | cut -d' ' -f1 | cut -d':' -f1)
                  if [[ -n "$backtick_text" ]]; then
                    echo "✅ Found backtick text: '$backtick_text'"
                    TESTS="$TESTS$backtick_text"$'\n'
                  else
                    echo "❌ No quotes found in line"
                  fi
                fi
              fi
            done <<< "$TEST_LINES"
            
            # Remove empty lines
            TESTS=$(echo "$TESTS" | grep -v '^$')
            echo "🔧 All extracted tests:"
            echo "$TESTS"
            if [[ -n "$TESTS" ]]; then
              echo "Found tests in $file:"
              echo "$TESTS"
              while IFS= read -r test_name; do
                echo "🔍 Processing test name: '$test_name'"
                if [[ -n "$test_name" && "$test_name" != *"it("* && "$test_name" != *"describe("* && "$test_name" != *"+"* ]]; then
                  # Escape special regex characters for Mocha grep
                  escaped_test=$(echo "$test_name" | sed 's/[[\.*^$()+?{|\\]/\\&/g')
                  echo "✅ Adding escaped test: '$escaped_test'"
                  if [[ -z "$CHANGED_TESTS" ]]; then
                    CHANGED_TESTS="$escaped_test"
                  else
                    CHANGED_TESTS="$CHANGED_TESTS|$escaped_test"
                  fi
                else
                  echo "❌ Skipping test name: '$test_name'"
                fi
              done <<< "$TESTS"
            else
              echo "❌ No test names extracted from $file"
            fi
          else
            echo "❌ File does not exist: $file"
          fi
        fi
      done <<< "$INTEGRATION_FILES"

      # Convert newline-separated files to space-separated, with quotes for safety
      echo "📋 Converting file list..."
      FILE_LIST=""
      while IFS= read -r file; do
        if [[ -n "$file" ]]; then
          FILE_LIST="$FILE_LIST \"$file\""
        fi
      done <<< "$INTEGRATION_FILES"
      echo "📋 Final file list: $FILE_LIST"
      
      echo "🧪 Final CHANGED_TESTS: '$CHANGED_TESTS'"
      if [[ -n "$CHANGED_TESTS" ]]; then
        # Remove leading pipe - no need for double escaping since we already escaped
        PATTERN="$CHANGED_TESTS"
        # CMD="npm run test:integration:only -- --grep \"($PATTERN)\" $FILE_LIST"
        CMD="npm run test:integration:only -- $FILE_LIST"
        echo "🎯 Running only changed test blocks with pattern: ($PATTERN)"
        echo "🚀 Command: $CMD"
      else
        CMD="npm run test:integration:only -- $FILE_LIST"
        echo "📂 No specific test blocks found, running all tests in changed files"
        echo "🚀 Command: $CMD"
      fi
      
      if [ "$WATCH" = "false" ]; then
        eval $CMD
      else
        npx nodemon --exec "$CMD" --ext '.test.ts'
      fi
    fi
  fi
}

Sample output

$ tdiff-integration 
Running specific integration test files:
__integrations__/users/api.test.ts
__integrations__/auth/service.test.ts
__integrations__/orders/controller.test.ts

🔍 Starting test name extraction...
📁 Processing file: __integrations__/users/api.test.ts
✅ File exists, getting git diff...
📝 Git diff output lines: 45
➕ Added lines count: 8
🧪 Test lines found: 1
🧪 Test lines content:
+    it("should validate user input", async () => {
🔧 Processing line: '+    it("should validate user input", async () => {'
✅ Found quoted text: 'should validate user input'
✅ Adding escaped test: 'should validate user input'

📁 Processing file: __integrations__/auth/service.test.ts
✅ File exists, getting git diff...
📝 Git diff output lines: 23
➕ Added lines count: 5
🧪 Test lines found: 1
🧪 Test lines content:
+  describe("#isAuthenticated", () => {
✅ Found quoted text: '#isAuthenticated'
✅ Adding escaped test: '#isAuthenticated'

📁 Processing file: __integrations__/orders/controller.test.ts
✅ File exists, getting git diff...
📝 Git diff output lines: 12
➕ Added lines count: 3
🧪 Test lines found: 0
❌ No test names extracted

🧪 Final CHANGED_TESTS: 'should validate user input|#isAuthenticated'
🎯 Running only changed test blocks with pattern: (should validate user input|#isAuthenticated)
🚀 Command: mocha --grep "(should validate user input|#isAuthenticated)" users/api.test.ts auth/service.test.ts orders/controller.test.ts

> Running tests...
  Users API
    ✓ should validate user input
  
  Auth Service  
    #isAuthenticated
      ✓ should return true for valid token
      ✓ should return false for expired token
      
  3 passing (45ms)