add initial rebase tests

Author: ds300

integration-tests/newIntegrationTest.ts

@@ -30,7 +30,7 @@ fs.writeFileSync(
 `,
 )
 
-spawnSafeSync("yarn", [], { cwd: testDir })
+spawnSafeSync("npm", ["i"], { cwd: testDir })
 
 // create shell script boilerplate
 fs.writeFileSync(

integration-tests/rebase-fast-forward-failures/__snapshots__/rebase-fast-forward-failures.test.ts.snap

@@ -0,0 +1,83 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Test rebase-fast-forward-failures: 00: when continuing the rebase, the final patch should fail to apply because it's out of date 1`] = `
+"SNAPSHOT: when continuing the rebase, the final patch should fail to apply because it's out of date
+patch-package 0.0.0
+• Creating temporary folder
+• Installing [email protected] with npm
+• Diffing your files with clean files
+✔ Created file patches/left-pad+1.3.0+002+world.patch
+
+Fast forwarding...
+
+⛔ ERROR
+
+Failed to apply patch file left-pad+1.3.0+003+goodbye.patch.
+
+If this patch file is no longer useful, delete it and run
+
+  patch-package
+  
+Otherwise you should open node_modules/left-pad, manually apply the changes from the patch file, and run
+
+  patch-package left-pad
+
+to update the patch file.
+
+END SNAPSHOT"
+`;
+
+exports[`Test rebase-fast-forward-failures: 01: when continuing the rebase, the final patch should apply 1`] = `
+"SNAPSHOT: when continuing the rebase, the final patch should apply
+patch-package 0.0.0
+• Creating temporary folder
+• Installing [email protected] with npm
+• Diffing your files with clean files
+✔ Created file patches/left-pad+1.3.0+003+goodbye.patch
+
+END SNAPSHOT"
+`;
+
+exports[`Test rebase-fast-forward-failures: 02: the patches should go from 'use strict' to 'use hello' to 'use universe' to 'goodbye universe' 1`] = `
+"SNAPSHOT: the patches should go from 'use strict' to 'use hello' to 'use universe' to 'goodbye universe'
+diff --git a/node_modules/left-pad/index.js b/node_modules/left-pad/index.js
+index e90aec3..1a2ec5f 100644
+--- a/node_modules/left-pad/index.js
++++ b/node_modules/left-pad/index.js
+@@ -3,7 +3,7 @@
+      * and/or modify it under the terms of the Do What The Fuck You Want
+      * To Public License, Version 2, as published by Sam Hocevar. See
+      * http://www.wtfpl.net/ for more details. */
+-'use strict';
++'use hello';
+ module.exports = leftPad;
+ 
+ var cache = [
+diff --git a/node_modules/left-pad/index.js b/node_modules/left-pad/index.js
+index 1a2ec5f..f2e3912 100644
+--- a/node_modules/left-pad/index.js
++++ b/node_modules/left-pad/index.js
+@@ -3,7 +3,7 @@
+      * and/or modify it under the terms of the Do What The Fuck You Want
+      * To Public License, Version 2, as published by Sam Hocevar. See
+      * http://www.wtfpl.net/ for more details. */
+-'use hello';
++'use universe';
+ module.exports = leftPad;
+ 
+ var cache = [
+diff --git a/node_modules/left-pad/index.js b/node_modules/left-pad/index.js
+index f2e3912..a02f494 100644
+--- a/node_modules/left-pad/index.js
++++ b/node_modules/left-pad/index.js
+@@ -3,7 +3,7 @@
+      * and/or modify it under the terms of the Do What The Fuck You Want
+      * To Public License, Version 2, as published by Sam Hocevar. See
+      * http://www.wtfpl.net/ for more details. */
+-'use universe';
++'goodbye universe';
+ module.exports = leftPad;
+ 
+ var cache = [
+END SNAPSHOT"
+`;