move tests to tests folder

rename util modules
rename DbUpload to DbUploader
add tests for DbUploader component #27

src/db.utils.js

@@ -0,0 +1,44 @@
+export default {
+  * generateChunks (arr, size) {
+    const count = Math.ceil(arr.length / size)
+
+    for (let i = 0; i <= count - 1; i++) {
+      const start = size * i
+      const end = start + size
+      yield arr.slice(start, end)
+    }
+  },
+
+  getInsertStmt (columns) {
+    const colList = `"${columns.join('", "')}"`
+    const params = columns.map(() => '?').join(', ')
+    return `INSERT INTO csv_import (${colList}) VALUES (${params});`
+  },
+
+  getCreateStatement (columns, values) {
+    let result = 'CREATE table csv_import('
+    columns.forEach((col, index) => {
+    // Get the first row of values to determine types
+      const value = values[0][index]
+      let type = ''
+      switch (typeof value) {
+        case 'number': {
+          type = 'REAL'
+          break
+        }
+        case 'boolean': {
+          type = 'INTEGER'
+          break
+        }
+        case 'string': {
+          type = 'TEXT'
+          break
+        }
+        default: type = 'TEXT'
+      }
+      result += `"${col}" ${type}, `
+    })
+    result = result.replace(/,\s$/, ');')
+    return result
+  }
+}