js/tools.js, tests: nice_min_max_step() yield no step when min = max

browser/js/tools.js

@@ -369,6 +369,9 @@ function nice_floor(x, force_pow10)
 
 function nice_min_max_steps(min, max, nb_max_steps)
 {
+    if (min == max)
+        return {min: min, max: max, step: 0, nb_steps: 0}
+
     var basic_step = nice_1_2_5_ceil((max - min) / nb_max_steps)
 
     var n_min = nice_floor(min, basic_step)

browser/test/QUnit/testFiles/tools_test.js

@@ -72,6 +72,8 @@ QUnit.test("test nice_min_max_steps", function(assert) {
 
     assert.deepEqual(nice_min_max_steps(43, 103, 5), {min: 40, max: 120, step: 20, nb_steps: 4}, "43..103 (5)");
     assert.deepEqual(nice_min_max_steps(43, 103, 3), {min: 0, max: 150, step: 50, nb_steps: 3}, "43..103 (3)");
+
+    assert.deepEqual(nice_min_max_steps(42, 42, 20), {min: 42, max: 42, step: 0, nb_steps: 0}, "42..42 (20)");
 });
 
 QUnit.test("prepend_path_if_not_web", function(assert) {