Add --no-overwrite flag to preserve target file

#1
center-key · Mar 17, 2024 · f320ff2 · f320ff2
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diff --git a/README.md b/README.md
@@ -45,13 +45,14 @@ You can also install **copy-file-util** globally (`--global`) and then run it an
 
 ### 3. CLI flags
 Command-line flags:
-| Flag       | Description                                    | Values     |
-| ---------- | ---------------------------------------------- | ---------- |
-| `--cd`     | Change working directory before starting copy. | **string** |
-| `--folder` | Indicates the target is a folder.              | N/A        |
-| `--move`   | Delete the source file after copying it.       | N/A        |
-| `--note`   | Place to add a comment only for humans.        | **string** |
-| `--quiet`  | Suppress informational messages.               | N/A        |
+| Flag             | Description                                    | Values     |
+| ---------------- | ---------------------------------------------- | ---------- |
+| `--cd`           | Change working directory before starting copy. | **string** |
+| `--folder`       | Indicates the target is a folder.              | N/A        |
+| `--move`         | Delete the source file after copying it.       | N/A        |
+| `--note`         | Place to add a comment only for humans.        | **string** |
+| `--quiet`        | Suppress informational messages.               | N/A        |
+| `--no-overwrite` | Abort if target file already exists.           | N/A        |
 
 Examples:
    - `copy-file app.js app.mjs --quiet`<br>
@@ -66,6 +67,9 @@ Examples:
    - `copy-file app.js --move --folder dist`<br>
    Like the `mv` Unix command.
 
+   - `copy-file default-config.json settings/config.json --no-overwrite`<br>
+   Performs a safe copy that aborts if the **settings/config.json** file already exists.
+
 _**Note:** Single quotes in commands are normalized so they work cross-platform and avoid the errors often encountered on Microsoft Windows._
 
 ### 4. Template variables

diff --git a/bin/cli.js b/bin/cli.js
@@ -27,7 +27,7 @@ import { dna } from 'dna-engine';
 import fs from 'fs';
 
 // Parameters and flags
-const validFlags = ['cd', 'folder', 'move', 'note', 'quiet'];
+const validFlags = ['cd', 'folder', 'move', 'no-overwrite', 'note', 'quiet'];
 const cli =        cliArgvUtil.parse(validFlags);
 const source =     cli.params[0];
 const target =     cli.params[1];
@@ -51,6 +51,7 @@ const targetKey = cli.flagOn.folder ? 'targetFolder' : 'targetFile';
 const options = {
    cd:          cli.flagMap.cd ?? null,
    move:        cli.flagOn.move,
+   overwrite:   !cli.flagOn.noOverwrite,
    [targetKey]: target.replace(/{{[^{}]*}}/g, getPackageField),
    };
 const result = copyFile.cp(source, options);

diff --git a/copy-file.ts b/copy-file.ts
@@ -14,12 +14,14 @@ export type Settings = {
    targetFolder:  string,   //destination folder for file copy operation
    fileExtension: string,   //new file extension for the target file
    move:          boolean,  //delete the source file after copying it
+   overwrite:     boolean,  //clobber target file if it exists
    };
 export type Result = {
    origin:   string,   //path of origination file
    dest:     string,   //path of destination file
    duration: number,   //execution time in milliseconds
    moved:    boolean,  //original file was deleted
+   skipped:  boolean,  //target file exists and was not overwritten
    };
 
 const copyFile = {
@@ -31,9 +33,10 @@ const copyFile = {
          targetFolder:  null,
          fileExtension: null,
          move:          false,
+         overwrite:     true,
          };
-      const settings = { ...defaults, ...options };
-      const startTime = Date.now();
+      const settings =        { ...defaults, ...options };
+      const startTime =       Date.now();
       const missingTarget =   !settings.targetFile && !settings.targetFolder;
       const ambiguousTarget = !!settings.targetFile && !!settings.targetFolder;
       const normalize = (folder: string | null) =>
@@ -47,6 +50,8 @@ const copyFile = {
       const targetFolder =   targetPath ? normalize(startFolder + targetPath) : null;
       const targetFile =     settings.targetFile ?? settings.targetFolder + '/' + sourceFilename;
       const target =         normalize(startFolder + targetFile);
+      const targetExists =   !missingTarget && fs.existsSync(target);
+      const skip =           targetExists && !settings.overwrite;
       if (targetFolder)
          fs.mkdirSync(targetFolder, { recursive: true });
       const badTargetFolder = !targetFolder || !fs.existsSync(targetFolder);
@@ -61,24 +66,28 @@ const copyFile = {
          null;
       if (errorMessage)
          throw Error('[copy-file-util] ' + errorMessage);
-      if (settings.move)
+      if (!skip && settings.move)
          fs.renameSync(source, target);
-      else
+      else if (!skip)
          fs.copyFileSync(source, target);
       return {
          origin:   source,
          dest:     target,
          moved:    settings.move,
+         skipped:  skip,
          duration: Date.now() - startTime,
          };
       },
 
    reporter(result: Result): Result {
+      // Example output:
+      //    [10:52:42] copy-file build/app.js → dist/app.js (1ms, moved)
       const name =   chalk.gray('copy-file');
       const origin = chalk.blue.bold(result.origin);
       const dest =   chalk.magenta(result.dest);
       const arrow =  chalk.gray.bold('→');
-      const info =   chalk.white(`(${result.duration}ms${result.moved ? ', move' : ''})`);
+      const status = result.skipped ? ', skip -- target exists' : result.moved ? ', move' : '';
+      const info =   chalk.white(`(${result.duration}ms${status})`);
       log(name, origin, arrow, dest, info);
       return result;
       },

diff --git a/spec/fixtures/target/skip/mock1.html b/spec/fixtures/target/skip/mock1.html
@@ -0,0 +1,11 @@
+<!doctype html>
+<html lang=en>
+   <head>
+      <meta charset=utf-8>
+      <title>📂📂📂 copy-file-util 📂📂📂</title>
+   </head>
+   <body>
+      <h1>📂📂📂 copy-file-util 📂📂📂</h1>
+      <h2>Copy or rename a file with optional package version number (CLI tool designed for use in npm package.json scripts)</h2>
+   </body>
+</html>
diff --git a/spec/fixtures/target/skip/mock2.html b/spec/fixtures/target/skip/mock2.html
@@ -0,0 +1,11 @@
+<!doctype html>
+<html lang=en>
+   <head>
+      <meta charset=utf-8>
+      <title>📂📂📂 copy-file-util 📂📂📂</title>
+   </head>
+   <body>
+      <h1>📂📂📂 copy-file-util 📂📂📂</h1>
+      <h2>Copy or rename a file with optional package version number (CLI tool designed for use in npm package.json scripts)</h2>
+   </body>
+</html>
diff --git a/spec/mocha.spec.js b/spec/mocha.spec.js
@@ -128,4 +128,16 @@ describe('Executing the CLI', () => {
       assertDeepStrictEqual(actual, expected);
       });
 
+   it('with the --no-overwrite flag prevents the target file from being clobbered', () => {
+      run('copy-file spec/fixtures/source/mock.html spec/fixtures/target/skip/mock1.html --no-overwrite --quiet');
+      run('copy-file spec/fixtures/source/mock.html spec/fixtures/target/skip/mock2.html --no-overwrite --quiet');
+      run('copy-file spec/fixtures/target/skip/mock1.html spec/fixtures/target/skip/mock2.html --move --no-overwrite');
+      const actual =   cliArgvUtil.readFolder('spec/fixtures/target/skip');
+      const expected = [
+         'mock1.html',
+         'mock2.html',
+         ];
+      assertDeepStrictEqual(actual, expected);
+      });
+
    });