feat(test): rest of test suite

spec/diff_spec.lua

@@ -2,41 +2,164 @@ describe('cp.diff', function()
   local diff = require('cp.diff')
 
   describe('get_available_backends', function()
-    it('returns vim and git backends')
+    it('returns vim and git backends', function()
+      local backends = diff.get_available_backends()
+      assert.same({'vim', 'git'}, backends)
+    end)
   end)
 
   describe('get_backend', function()
-    it('returns vim backend by name')
-    it('returns git backend by name')
-    it('returns nil for invalid name')
+    it('returns vim backend by name', function()
+      local backend = diff.get_backend('vim')
+      assert.is_not_nil(backend)
+      assert.equals('vim', backend.name)
+    end)
+
+    it('returns git backend by name', function()
+      local backend = diff.get_backend('git')
+      assert.is_not_nil(backend)
+      assert.equals('git', backend.name)
+    end)
+
+    it('returns nil for invalid name', function()
+      local backend = diff.get_backend('invalid')
+      assert.is_nil(backend)
+    end)
   end)
 
   describe('is_git_available', function()
-    it('returns true when git command succeeds')
-    it('returns false when git command fails')
+    it('returns true when git command succeeds', function()
+      local mock_system = stub(vim, 'system')
+      mock_system.returns({ code = 0 })
+
+      local result = diff.is_git_available()
+      assert.is_true(result)
+
+      mock_system:revert()
+    end)
+
+    it('returns false when git command fails', function()
+      local mock_system = stub(vim, 'system')
+      mock_system.returns({ code = 1 })
+
+      local result = diff.is_git_available()
+      assert.is_false(result)
+
+      mock_system:revert()
+    end)
   end)
 
   describe('get_best_backend', function()
-    it('returns preferred backend when available')
-    it('falls back to vim when git unavailable')
-    it('defaults to vim backend')
+    it('returns preferred backend when available', function()
+      local mock_is_available = stub(diff, 'is_git_available')
+      mock_is_available.returns(true)
+
+      local backend = diff.get_best_backend('git')
+      assert.equals('git', backend.name)
+
+      mock_is_available:revert()
+    end)
+
+    it('falls back to vim when git unavailable', function()
+      local mock_is_available = stub(diff, 'is_git_available')
+      mock_is_available.returns(false)
+
+      local backend = diff.get_best_backend('git')
+      assert.equals('vim', backend.name)
+
+      mock_is_available:revert()
+    end)
+
+    it('defaults to vim backend', function()
+      local backend = diff.get_best_backend()
+      assert.equals('vim', backend.name)
+    end)
   end)
 
   describe('vim backend', function()
-    it('returns content as-is')
-    it('returns nil highlights')
+    it('returns content as-is', function()
+      local backend = diff.get_backend('vim')
+      local result = backend.render('expected', 'actual')
+
+      assert.same({'actual'}, result.content)
+      assert.is_nil(result.highlights)
+    end)
   end)
 
   describe('git backend', function()
-    it('creates temp files for diff')
-    it('returns raw diff output')
-    it('cleans up temp files')
-    it('handles no differences')
-    it('handles git command failure')
+    it('creates temp files for diff', function()
+      local mock_system = stub(vim, 'system')
+      local mock_tempname = stub(vim.fn, 'tempname')
+      local mock_writefile = stub(vim.fn, 'writefile')
+      local mock_delete = stub(vim.fn, 'delete')
+
+      mock_tempname.returns('/tmp/expected', '/tmp/actual')
+      mock_system.returns({ code = 1, stdout = 'diff output' })
+
+      local backend = diff.get_backend('git')
+      backend.render('expected text', 'actual text')
+
+      assert.stub(mock_writefile).was_called(2)
+      assert.stub(mock_delete).was_called(2)
+
+      mock_system:revert()
+      mock_tempname:revert()
+      mock_writefile:revert()
+      mock_delete:revert()
+    end)
+
+    it('returns raw diff output', function()
+      local mock_system = stub(vim, 'system')
+      local mock_tempname = stub(vim.fn, 'tempname')
+      local mock_writefile = stub(vim.fn, 'writefile')
+      local mock_delete = stub(vim.fn, 'delete')
+
+      mock_tempname.returns('/tmp/expected', '/tmp/actual')
+      mock_system.returns({ code = 1, stdout = 'git diff output' })
+
+      local backend = diff.get_backend('git')
+      local result = backend.render('expected', 'actual')
+
+      assert.equals('git diff output', result.raw_diff)
+
+      mock_system:revert()
+      mock_tempname:revert()
+      mock_writefile:revert()
+      mock_delete:revert()
+    end)
+
+    it('handles no differences', function()
+      local mock_system = stub(vim, 'system')
+      local mock_tempname = stub(vim.fn, 'tempname')
+      local mock_writefile = stub(vim.fn, 'writefile')
+      local mock_delete = stub(vim.fn, 'delete')
+
+      mock_tempname.returns('/tmp/expected', '/tmp/actual')
+      mock_system.returns({ code = 0 })
+
+      local backend = diff.get_backend('git')
+      local result = backend.render('same', 'same')
+
+      assert.same({'same'}, result.content)
+      assert.same({}, result.highlights)
+
+      mock_system:revert()
+      mock_tempname:revert()
+      mock_writefile:revert()
+      mock_delete:revert()
+    end)
   end)
 
   describe('render_diff', function()
-    it('uses best available backend')
-    it('passes parameters to backend')
+    it('uses best available backend', function()
+      local mock_get_best = spy.on(diff, 'get_best_backend')
+      local mock_backend = { render = function() return {} end }
+      mock_get_best.returns(mock_backend)
+
+      diff.render_diff('expected', 'actual', 'vim')
+
+      assert.spy(mock_get_best).was_called_with('vim')
+      mock_get_best:revert()
+    end)
   end)
 end)